NOTE: This is split into two writeups, as I appear to have hit the 64K writeup size limit. :-)

E2 Introduction: This is a paper I once wrote for a course on military analysis at MIT. I offer it here not to tout its conclusions, but to give those people interested in the process of military analysis an example of the less formal but still informational end of the analytic spectrum. As I have not modified the paper in any way save typographically for web presentation, the astute reader will note differences between my predictions of 1995 and how the world turned out! I hope this is useful for those curious noders who have asked me, in earnest, "What does a military analyst do, precisely?" Here's a school/training example.

The Back of the Envelope


Sizing the U.S. Navy SSN Force for the 21st Century


The Custodian
Spring 1995

The United States exited the Cold War era with a large inventory of weapon systems designed to fight a conflict that never came. In recent years, downsizing has been the watchword in the military, and the U.S. is shedding forces at a rate unmatched since the close of World War II. The problem, however, is that the rationales for the target force levels are not always backed up by analysis that is visible to the public.

This paper concerns a narrow part of the U.S. armed forces; the nuclear attack submarine (SSN) force of the U.S. Navy. This force consists, presently, of eighty-five nuclear submarines, expensive to buy and expensive to operate. The Navy has decided, in numbers released for public consumption, that it needs between forty-five and fifty-five of these submarines. It does not, however, provide arguments as to why that is so, other than to state that that is the force level required to 'prosecute two major regional conflicts and to meet peacetime requirements for overseas presence, while ensuring that an adequate rotation base is available to support Navy and U.S. Marine Corps goals for personnel operating tempo.'1

My question is a simple one: How many attack submarines does the U.S. need, and why? To answer this question I will take the proposed National Security Strategy and offer a method of determining how many attack submarines the nation needs. I will begin with a brief examination of the national strategy. This will not be a critique, as whether or not I agree with the strategy, it is the base that the Navy has apparently used to determine a required force size of 45-55 boats. The goal of this paper is to use the requirements of the strategy to 'back into' a total number of SSNs required.

Following the examination of the existing U.S. strategy, I will briefly describe the current U.S. SSN force and its capabilities, since it is from these existing assets that the U.S. Navy will choose the boats it will retain to comprise its force in the near term. Then, in the main component of this analysis, I will attack the problem by asking, 'What are SSNs good for? Given the answer to that question, how much of that answer will the U.S. want to do in the future?'

Once I have arrived at a number of continuously deployed SSNs required and a maximum number of temporarily deployed SSNs for each category, I will address the issues of mission category overlap and the number of boats that must be in the force to maintain the required number available - the 'deployment ratio.' With that number in hand, I will combine the answers and come up with some recommendations for sizing the force in the immediate future.

With the structure of this analysis set down, I will begin with the National Security Strategy, and the Navy's own piece of it, '...From the Sea.'

Current Strategy

It is my contention that the U.S. can no longer simply size its SSN force as a best effort to meet the maximum threat. The collapse of the Soviet Union makes any scenario involving the U.S. Navy engaging in direct combat with the Soviet surface and submarine fleets extremely unlikely. Therefore, simply producing as many submarines as we are able in order to meet a constantly numerically superior force (regardless of the correctness of this approach in the past) can no longer even be used as a rationalization. A more careful approach is required.

Although any attempt to size the SSN force must by definition take into account external threats, it no longer must or even should assume that these threats are beyond the ability of the United States to 'choose.' That is, although there are still missions for our SSN force to undertake (and as I argue below, a wider variety of missions) they will be undertaken as a result of national choice rather than in reaction to a large direct threat to or attack on the United States or its Navy. Therefore thinking about these problems requires, as a prerequisite, a concept of the grand strategy of the United States. It is impossible to determine how many boats you will need to perform your required missions if you do not know how many of these missions you will need to carry out. In the past, the number of missions could be relatively easily derived from the size of its primary opponent, the Soviet submarine force. Thinking of the SSN force as purely an ASW asset is, however, what Ronald O'Rourke of the Congressional Research Service has labelled an 'Old Habit of Thought.'2 Now, with the variety of tasks assigned to it, the attack sub force must have a clearer picture of the scope of its activities.

For the purposes of this analysis, I have chosen to utilize an existing strategic guideline, the National Security Strategy as taken from the February 1995 Annual Report to the President and the Congress from the Secretary of Defense. I am not endorsing it as correct; since an evaluation of the grand strategy of the U.S. is beyond the scope of this paper I am utilizing it only as an input for the crude force sizing analysis presented here.

The Annual Report discusses the President's National Security Strategy in the context of the requirements it places on the Department of Defense. The major themes of the strategy, presented in abbreviated form therein, are those of 'engagement' and 'enlargement.' The first means that the United States will remain 'engaged' in world affairs, and the second states its intention to enlarge a 'community of free-market democracies around the globe,' which would be familiar to Kant. The methods for achieving these goals are, respectively, to maintain a strong defense of the U.S. and its interests, and therefore to retain the capability to 'influence the policies and actions of others beyond its borders.'3 The most specific requirement for this capability is that the U.S. need to be able to prevent regional hegemons from gaining control over U.S. interests in their local area.

This is fairly vague, but some threads can be drawn from it. First, although the strategy mentions a strong defense of the U.S., it also speaks at length about building a 'successful defense and military partnership with Russia, Ukraine and the other New Independent States of the former Soviet Union' as a high priority.4 We can assume, therefore, that regional forces are the most likely threat that the DoD anticipates facing in the execution of this strategy. Furthermore, there is no mention of a need to be able to 'dictate' events. While 'influence' is vague, we can assume that there is unlikely to be a requirement for U.S. forces to assume positive control over large, hostile, populated areas of other nations.

There is mention of 'protecting democracies,' which implies the possibility of large-scale intervention in democratic nations under attack or otherwise in danger. However, given recent past U.S. efforts, these contingencies are unlikely to involve extremely long term commitment of forces and will probably not concern the attack submarine force to a great degree. In discussion of the Major Regional Contingencies, the requirement is to quickly settle the matter in both of the MRCs that the military appears to be planning to fight.5

This means, for our purposes, the following: First, there is little chance of a major battle, surface or subsurface, for the blue water of the world. Strategic ASW, SLOC protection and hunting down large numbers of enemy SSBNs are not missions that our nominal SSN force should be optimized for, especially since in whatever form it eventually takes it will retain capability for this task; capability which would be considerable with the force at maximum effort.

In the Annual Report, Secretary of Defense Perry notes that one of the three primary challenges for the U.S. is to reformulate its policies for the use or threat of use of its military power. Three levels of threat are presented in that document, in descending order from 'vital U.S. interests threatened' to contingencies of 'strictly humanitarian concern.' Even in the most serious, the most significant use of military power offered as an example was not an actual conflict, but the 'Operation Vigilant Warrior' reinforcement in response to Iraq's troop movements on the Saudi Arabian and Kuwaiti borders.6

In terms of grand strategy, we are on shaky ground. The means which the U.S. would appear to stand ready to use are limited ones, and the goals are in fact unclear. Perhaps a better way to approach the problem of what the Navy plans to do in relation to this strategic statement would be to turn to '...From the Sea,' the Navy and Marine White Paper which purports to explain the direction those services are looking to in their attempt to describe the future.

From the Sea is not a strategy, nor is it a complete doctrine. It does not outline a set of overall goals for the nation. Nor does it provide information in any really useful depth as to how the Navy and Marine Corps plan to conduct the operations which it discusses. Nevertheless, it provides useful indicators.

Central to the document and contained in its title and authorship is the notion that the real 'business' of the Navy can no longer really be justified in terms of blue-water dominance, or sea control. As the Navy puts it, 'our [existing] ability to command the seas in areas where we anticipate future operations allows us to resize our Naval Forces and to concentrate more on capabilities required in the complex operating environment of the 'littoral' or coastlines of the earth.' It goes on to note that 'This strategic direction, derived from the National Security Strategy, represents a fundamental shift...toward joint operations conducted from the sea.'7

The paper lists operational capabilities which the Navy must be able to field in order to carry out the requirements in this paper. The three that concern an examination of the attack submarine force are: Command, control, and surveillance, battlespace dominance, and power projection.8 These are the three areas in which attack submarines can contribute capability.

Surveillance is an area where the attack submarine, with its natural stealth, is a highly capable asset. Battlespace dominance refers to the ability to control the area of blue water, littoral and coast where U.S. assets are or from which force are being projected ashore. This implies ASW and ASuW missions to secure the forces going ashore, and possibly interdiction of any sea-based reinforcement or resupply of the enemy forces. It may also include land attack missions as part of an effort to suppress coastal and air defenses in order to secure the attacking force. Power projection ashore is now, with SLCMs and SEAL special operations teams, a capability fielded by the SSN.

Combined with the examination of the National Security strategy above, we have a picture from which the following points can be drawn:

  • Threats to its blue water dominance will not be a primary factor for the U.S. Navy, at least in the near future. Thus, strategic ASW and ASuW vs. major combatants are not expected to occur on the scale previously assumed during the Cold War.
  • Most of the Navy's 'interesting' assets, those which they base their most visible procurement requests on, will be involved in these littoral operations, projecting power from the sea, into the littoral and onto the land. Thus, we can foresee Naval assets performing missions to support this type of mission or 'battlespace' as the Navy terms it, in a local area.
  • There will be a requirement for forces which can perform power projection missions at all levels of involvement, from small limited strikes to full amphibious operations.

I have discussed specific mission requirements here. Description of mission types, and probable frequency, are discussed in the explanation of my sizing model. I have strayed into this examination of the U.S.'s National Security Strategy and the Navy's response to it in order to provide a context for determining 'how involved' the U.S. has chosen or will choose to be, which will assist us later in coming up with the number of various missions (or deployed boats) we will need.

The current SSN force of the U.S. Navy consists of some eighty-five boats. In order to best determine what these boats are capable of and which are best suited for future U.S. requirements, I will briefly go over the boats in inventory and discuss their relevant characteristics.

The Current Force

Most prevalent in the force today is the most modern boat, the SSN-688 Los Angeles-class submarine. Generally named for U.S. cities, these submarines are the result of a large program which is just now coming to a close, with the remaining boats of the class due to be delivered in 1996. The final units of the run were cancelled due to budgetary constraints.


The 688 (Los Angeles) class

The 688 class has three subclasses: the 688 Flight I, the 688 Flight II, and the 688I (Improved.) Fifty-five boats of these three classes remain in service with 31 of them of the Flight 2 or Improved class.9 The 688 boat is the premier U.S. SSN currently deployed; it was designed as an open-ocean ASW platform , to track and attack Soviet Navy SSBNs, SSGNs and SSNs. For our purposes, it should be enough to note that it is capable of a wide range of missions. It contains the latest U.S. sensor suite, and can employ Mk. 48 ADCAP and older torpedoes, tube-launched UGM-65 Harpoon antiship missiles and tube-launched Tomahawk missiles, both of the TLAM and TASM variant (although I was told by several submariners that the TASM is no longer deployed or utilized in training, in favor of the Harpoon.)10 In addition, the Flight II and Improved boats carry 12 Tomahawk SLCMs in VLS cells in the bow for land strike missions. The 688 boats are the newest in the force, with the oldest unit launched in 1974 and commissioned in 1976.


The SSN 637 (Sturgeon) class/SSN 671 (Narwhal) class

Twenty-seven boats remain in these two classes. The Narwhal is a modified Sturgeon boat, used for powerplant and other system R&D, but still an active SSN. These boats were produced immediately prior to the 688 boats, and those near the end of the run, while older than the 688's, may have been refueled recently, making them more worth retaining.

These boats have essentially the same weapon types as the 688s, as they are able to employ the Mk. 48 ADCAP, the Harpoon, and the Tomahawk. However, all of their munitions must use the 533mm torpedo tubes (they do not carry VLS) and their load is smaller than the 688. In order to ship Tomahawks, they must offload torpedos and/or Harpoons. Most important, however, they do have the systems required to target and launch the Tomahawk. (NOTE: This refers to the older, TERCOM / DSMAC guided versions of the Tomahawk.)


The SSN 615, USS Gato

Bearer of a proud name from World War II, the Gato is the sole remaining Permit class boat from the 1960's. She is armed with four Harpoons, as well as Mk. 48 class weapons.


The Benjamin Franklin conversions

Two of the original Polaris/Poseidon boats of the Franklin class have been converted to SSNs by removal of the missile section and refurbishing. These two boats, SSN 642 and SSN 645, although designated SSN and retaining their 533mm tubes for Mk. 48 class weapons, are primarily special operations boats. Each will be able to carry two DDS (Dry Deck Shelters) capable of carrying 67 SEALS and their equipment, and providing access to and from the SSN while submerged.

This produces, as noted, a total of eighty-five boats. With fifty-five of them in the newest class of submarine, it is clear that there is no reason that trimming the force will result in a degradation of the quality of boats deployed. On the contrary, if the U.S. were to deactivate boats in the order received, it would decrease the average age and increase the average capability of the force. As mentioned above, the exception to this policy that would make sense might be to retain older boats that have recently been refueled, in order to avoid paying for the refueling of the early 688 boats which is now coming due (SSN 688, the Los Angeles, will be twenty years old in 1996.)

Since my purpose is to discuss the future of the U.S. SSN force, I will devote some space to the description of those types of submarines projected to be added to the force over the next decade or two. I will not attempt to project numbers at this time.


The SSN 21 (Seawolf) class

Follow-on to the 688 boat, the Seawolf is currently the subject of heated debate in American budgetary and defense policy circles. It has come under attack for two primary and related reasons. One, each boat costs around $2.2 billion in 1993 dollars ($2.8 billion for SSN 21 and 22 after overruns.)11. Two, it was designed and procured to defeat the newest Soviet (now Russian) fleet designs, a threat which most consider much less likely to materialize opposite the U.S. Navy in the future. Two boats are currently building, SSN 21 and SSN 22. The current plan is to acquire one more unit in 1996 to maintain workload for the Electric Boat yard until the New SSN production begins in 1998.12

The Seawolf, consonant with its purpose as counter to newer ex-Soviet boat designs, is principally an ASW platform. Much of the R&D resources went into improved quieting, allowing the boat to travel quietly at up to 20 knots. Although it does not have VLS cells, its internal weapon load is larger than that of the 688. It is to have eight 762mm torpedo tubes, and can carry up to a fifty-weapon mix of Tomahawk, Harpoon and Mk. 48 class weapons, or 100 mines.


The New SSN (NSSN) class

Although the debate about Seawolf rages on, work is already underway on the next class of attack submarine. This ship is designed to address the primary defect of Seawolf, its cost; its design goals are to retain the quieting features of the more expensive boat in a smaller, less capable but cheaper package. Even the major characteristics of the boat's capabilities have not been worked out, however, as the existence of the program is subject to uncertainty.


The SSXN Class

...and it doesn't stop there. Design work is also underway on the successor to the New SSN, the SSXN, named for the proposed modular nature of the design. If incorporated, the basic submarine hull would be fitted for different missions (and classes) by the inclusion of one of a variety of hull sections, each optimized for a different job. For example, the SSFN would be a special operations boat, with SEAL accomodations and a swimmer lock. The SSMN would be specialized for mine warfare and mine countermeasures, possibly using remotely piloted vehicles. The SSLN would be dedicated to land attack, carrying as many as 75 to 100 Tomahawks, presumably in VLS cells. For C3I and electronic warfare, a version called SSCN is proposed. SSKN would be a 'blue-water' maritime surveillance and sea control sub, and SSTN would either fire or defend against theater ballistic missiles; it isn't quite clear. There would be an SSBN version as well.13

It may be premature to discuss the impact the Seawolf class may have on the fleet, with only three boats by even the optimistic Navy planners' projections. Certainly it will be a capable boat; however, for many of the missions it will be expected to perform, less capable and less expensive boats may do just as well. Even were there to be a resurgence of the Russian submarine threat, it is difficult to see how a three-boat force could make a difference against any planned effort. With three boats, they would provide a 'silver bullet' capability in much the same fashion as the Air Force's F-22 - although against what threat is unclear.

The NSSN is itself in trouble. With the cost of a downgraded NSSN, with capabilities roughly equivalent to a 688I, being projected at $1.2 billion (twice the cost of the 688I) it will need work before it is feasible. For this reason, I will not devote much time or space to the expected uses of the NSSN in our nominal future U.S. SSN force; when whatever unit is eventually produced does begin arriving, it will no doubt be used to replace the Los Angeleses which will, by the turn of the century, be twenty-five years old, with only five to fifteen years of life left in them even with major overhauls.

688 boats are quite capable. Stock boats of this class have ASW, ASuW, land attack and some intelligence capabilities; enhanced intelligence or special operations capabilities may be easily added to any of them using existing upgrades such as the Dry Deck Shelter. Boats thus equipped would be in a position to replace the older Sturgeon and Franklin class special operations boats, although with more limited underway time there is no reason that the boats already modified should not last a decade or more, depending on their fueling status. Later 688s have improved land attack through their VLS cells as well as a mining capability.

The Sturgeons are older, and it shows. Their weapons load is smaller, and none of them have VLS. Their fire control and sensor suites are older. However, even given all these, they are still excellent ASW, ASuW, intelligence gathering and special operations assets.

Since these two classes alone represent nearly the entirety of the existing fleet, there is no reason to examine older boats; any force retained would be drawn from these assets.

The Missions

The first question, when discussing the size of the attack submarine force, is a basic one: what are they good for? Answering this question is the first step in deciding how many you need. In this section, I shall attempt to translate those technical capabilities just described into actual mission capabilities, which may then be compared with mission requirements later on in the analysis.

Perhaps the best place to start is to examine the traditional roles of the submarine. Starting with World War I, the submarine underwent several major changes in its roles and missions, due to both technological and political changes. At the outset of World War I, the submarine was just beginning to join the fleets of the world in significant numbers, but its mission was still unclear. The British, possessors of some of the finest boats, relegated them to the bottom of the Navy 'status pole.' Perhaps the best explanation for this is that the British Navy had traditionally maintained control of the seas through its surface battle fleet. The submarine represented a threat to that fleet, and it was one that was much cheaper to build, crew and maintain. Faced with a threat to their traditional dominance of the oceans, the British may have entered a state of denial which led Admiral A.K. Wilson to dismiss the submarine as 'underhand, unfair, and damned un-English.'14 This was not just hyperbole; as the world's premier Navy, the RN had some large influence on the naval strategy of other nations, and the use of any means by which they might suppress the spread of this threat is understandable.

Others, who weren't English in any case, did not feel put off by this, and during World War I, German submarines wreaked havoc on Atlantic sea lanes in an effort which has been well chronicled elsewhere. Their initial deployment agaist commercial shipping was hampered by the Kaiser's insistence that they adhere to the internationally recognized rules of cruiser warfare, which required them to surface and warn their intended victim so as to allow evacuation. This, by eliminating their chief weapon, stealth, had predictable negative impact on the U-boat's effectiveness. It was not until unrestricted submarine warfare became the norm later in the war that the submarine had the impact on the course of events that it would continue to exhibit into World War II.

By World War II, forgetting lessons learned, the U.S. Navy had assigned its submarines to be scouts for the surface fleet. They were saved being employed in this reconaissance role by Pearl Harbor, which left the U.S. Pacific Fleet temporarily without a surface force for which the submarines might scout. They were turned loose for unrestricted submarine warfare against Japan immediately, paralleling strategies that had been in use against the Allies in the Atlantic since the beginning of the war by Doenitz's U-Boats.

In any case, at the close of World War II, the accepted role of the submarine was that of commerce raider. The guerre de course

The technological developments that were to change the role of the submarine dramatically were the development of nuclear weapons, the development of nuclear propulsion, and the development of the missile-launching submarine. With these three advances, the submarine suddenly became a threat to land targets, a threat able to deliver nuclear weapons, and one that had suddenly become much stealthier with the advent of nuclear propulsion. As a result, the roles that submarines were expected to play changed and expanded. On the Soviet side, submarines were quickly adapted to launch missiles against surface targets, albeit with varying success. Mated with the cruise missile and the nuclear warhead, even with rudimentary guidance, the SSGN was developed to counter the threat posed by the U.S. Navy's large-deck carriers. Ballistic missile technology was added to produce the SSBN. Suddenly, ASW had ceased to be a point defense operation intended to prevent subs from executing relatively short-ranged attacks on surface targets. It had become the much more difficult task of hunting submarines not only farther from your surface combatants but in the open seas where they were hiding from your forces while waiting to launch weapons against your homeland.

Since the number of surface combatants was limited, especially given their need to travel in groups, and the short endurance of aircraft prevented them from becoming a frontline strategic ASW asset until detection technologies and aircraft range and numbers increased during the Cold War, the natural asset to hunt submarines was another submarine. The SSN's primary mission became the destruction of other submarines of all types. Due to its stealth and endurance, it could deploy far forward in order to track enemy submarines near their ports without being detected, and could prosecute targets for an essentially indefinite period of time.

Given that the primary task of the NATO navies opposing a land-based power was to protect the SLOCs, from early on U.S. SSNs were dedicated ASW platforms. Even the size of their torpedo warheads decreased due to the weaker submerged hulls that they were expected to be used against.

Originally, I had intended to pursue a purely quantitative model to determine force sizing, using as inputs variables such as boat endurance, transit time, weapons carried, strikes required, attrition and the like. Robert Kuenne uses this method in analyzing the performance of the German and American submarine forces in World War II. Barry Posen uses numerical modelling to analyze NATO barrier defense ASW performance versus Warsaw Pact submarine forces in a hypothetical NATO/Pact conflict. While these models perform quite well, in the course of my attempts to model the problem of sizing a contemporary U.S. SSN force I came to realize that this approach is not as directly applicable. The two situations analyzed by Kuenne and Posen share characteristics not found in my problem.

In the World War II and Cold War models, each analyst is examining a period of sustained maximum effort, limited only by resources. In addition, the conflict modelled is not expected to change in intensity for reasons other than war termination or material attrition. Barry Posen notes at the beginning of his chapter on Sea Control that the purpose of his analysis is to discuss the relative merits of two proposed methods of keeping the SLOCs open in time of general NATO/PACT conflict.16 Robert Kuenne, in his introduction, outlines his work as a analysis of the strategies adopted by the combatant nations in World War II for employment of their attack submarine fleet.17

In the present case, that of sizing the U.S. SSN force during peacetime, the force in question is not presently engaged in a maximum-effort conflict. Furthermore, as discussed earlier, the likelihood of its finding itself in such a situation in the foreseeable future is small. Therefore, when defining tasks and missions, there is no single target or adversary that can be assumed; nor can we even assume that there will be any adversary or target set present at all times. The force size is dependent on the mutable requirements generated by U.S. foreign policy and strategy to a greater degree than it is on any existing system that can be neatly quantified, such as the Soviet submarine fleet or Japanese merchant shipping and escort vessels.

For these reasons, I have backed away from a purely quantitative model, and propose the following. Earlier, I laid out the technical capabilities of the boats presently in the U.S. inventory, and those projected to be so in the near future. I also discussed present and future U.S. strategy, at least that part of it which is available and decipherable. In this section, I plan to discuss each of the broad technical mission capabilities of U.S. boats, and in context of each capability examine the likely requirements that would call for its use. International and domestic political factors will be married to available historical evidence to produce rough estimates of U.S. requirements for each mission capability. Finally, the numbers for all capabilities will be summed and examined for possible mission overlap, to come up with a final number of boats which the U.S. needs to be able to maintain at sea or 'deployed.' Once that number is available, I will examine the effects of peacetime versus regional crisis situations, and other possible reasons that number might jump sharply, and how the U.S. might best deal with that possibility. Finally, I will examine how many boats the force needs, total, in order to maintain our given requirement of boats deployed (the 'deployment ratio'), and the effect various conditions might have on that ratio.

Asst. Secretary of the Navy Nora Slatkin, in testimony before the Subcommittee on National Security of the House Appropriations Committee, recently displayed an overhead listing those mission requirements the Navy saw as crucial for the submarine force:18

While these are interesting, the first is so vague as to be of little use to us, and the second category presents a hodgepodge of mission requirements. I propose the following categories of mission, each of which will be further subdivided: Escort, ASW, ASuW, Land Attack, Intelligence, Special Operations, and Forward Presence. I have chosen these categories as they are divided more along capability lines than the previous array.

Escort Duties

Broadly defined, I use escort duties to describe any mission in which an SSN is attached to another asset, surface or submarine, in order to protect it. This has typically included, in the past, Carrier Battle Groups, SSBNs and other high-value assets. In the future, I assume that it may include the following subcategories, and will discuss each in turn:

  • Carrier Battle Groups (CVBG)
  • SSBNs
  • Naval Expeditionary Forces, as outlined in 'From the Sea.'
  • MPS vessels and other shipping, either U.S. or Allied, in hostile regions.

CVBGs
Aircraft carriers are a high-value asset. In addition, they are essentially armed only with their air wing; modern CVNs carry only point-defense anti-air weapons.19 Therefore, they travel in battle groups, with a varying number of escort vessels to provide ASW and air defense (AA). In the past, SSNS have been assigned as CVBG escorts, designated to coordinate their ASW activities with the CVBG surface escorts and ASW aircraft. In the future, one source states, due to the declining numbers of surface combatants, two SSNS per CVBG will be assigned as ASW protection.20

The US Navy anticipates having 11 'active' carriers in the future, allowing three CVBG's to be continuously deployed. At two SSNs per CVBG, that leads to a requirement of six continuously deployed SSNs, year round. I take three forward deployed CVBGs as a likely number for the U.S. Navy. I have difficulty determining why two SSNs per group would be required. Although deck loading on the carriers has decreased, there would still be between 6 and 8 S-3 Viking ASW aircraft per carrier air wing, as well as 5 SH-60 helos which have ASW capabilities.21 The major thrust of longer-range ASW efforts from CVBGs was designed to counter not torpedo attacks but cruise and sea-skimming missile attacks from Soviet (now Russian) SSGNs and SSNs. Since the Navy is poised to transition CVBGs to a littoral, power projection role rather than a blue-water sea control and deep strategic attack role such as they held during the Cold War, a hard look should be taken at the threats these assets are likely to encounter.

Although much advanced weaponry has proliferated to smaller nations who are more likely to employ them in regional conflict, there is no indication that the more expensive nuclear or conventional cruise missile submarines have so spread. The longest range weapon that can reasonably be expected to be deployed on the conventional SS of the 'regional aggressor' is an encapsulated sea-skimming weapon, such as a sub-launched Exocet or AGM-84 Harpoon. These weapons all have ranges of 70 nm or less. Since Soviet sea-launched antiship cruise missiles had considerably longer range,22 it does not appear likely that the expected long-range submarine threat to a CVBG has increased; rather, it appears to have lessened. Given the difficulty in distinguishing one submarine from another, especially from a surface platform, in a combat environment, it is likely that any SSNs attached to a CVBG would be given operating zones in order to ensure their safety, and that this zone would be a safe distance from the operating zone of surface ASW escorts and ASW air activity. The most likely employment for SSNs attached to CVBGs would be to sweep the area(s) ahead to the group in order to search for and prosecute possible submarine contacts at ranges beyond that of the surface escorts' capabilities; perhaps to act in concert with air ASW assets to 'sanitize' the expected path of the carrier. As such, it would be expected to provide early warning and protection from distant SSGN and long-range SSN attacks. Given the number of helos deployable from the CV or CVN and its escorts, close-in ASW probably is a relatively indiscriminate affair. Therefore, the CVBG escort task for which the SSN has been suited, long range anti-SSGN and anti-SSN patrol, is not a threat that has increased but rather decreased.

I would hold that one SSN maximum per CVBG would be sufficient. Since the submarine threat to the CVBG is more likely now one of a quiet, bottom-sitting conventional boat that would be forced to make its attack closer in to the carrier, an increase in close-range, indiscriminate ASW assets such as helos would appear to be a more sensible option. Therefore, I allocate three continuous SSN deployments, total, to CVBG escort duties to handle three groups. Since the U.S. Navy has demonstrated its tendency to 'double up' carriers for major contingencies rather than sortie two groups, additional CV or CVN assets are essentially being protected by the same force in some cases of increased tempo.

SSBNs
The American SSBN is traditionally a creature of stealth and solitude. I have been unable to find any indication that, other than in exercises, the Navy planned to provide escorts for SSBNs on patrol. The exercises mark those designed to allow SSNs to 'shepherd' SSBNs in time of conflict23, and during the two times they are most vulnerable- when entering and leaving port. Since the SSBN depends on its stealth to protect it, and these are the only two times its location can reasonably be predicted by enemy forces, it makes sense to escort SSBNs in and out of port in order to ensure their safety. However, two factors should be considered. One, although it is not an impossibility, the current strategy does not project entering into such a conflict (especially not with regularity!) in the near future. Secondly, the point of having at-sea SSBNs is so that in time of crisis which might presage American SSBNs being attacked entering or leaving ports, enough boats are already at sea to mitigate any damage that might be done to the force.

I would estimate that two SSNs would be enough to cover a departing or arriving SSBN, utilizing 'sprint and drift' tactics with one SSN listening and one SSN in transit to the front of the 'convoy.' In any case, I do not consider this a mission which it is necessary to maintain deployed SSNs to perform in any except the gravest crisis. If it became necessary to surge the force, then two SSNs would serve to protect all SSBNs leaving a given port, and once they had made their exit would be released for other duties.

Naval Expeditionary Forces
This is a sort of 'catch-all' sub-category, as it can, according to the Navy, include anything from a couple of Tomahawk-equipped destroyers to a full amphibious assault group mated with a CVBG and supporting craft. In any case, however, assets assigned to an EF would be deployed as a group. There are two types of operations which we need to consider. The first is simply an offshore presence or land strike mission, in which all combatants remain off the coast and no vessels or personnel go ashore. The U.S. Tomahawk strike on Iraq following the discovery of the 'Bush assassination plot' is one example. The second is a full 'from the sea' operation, involving amphibious forces transiting from blue-water to the littoral and across a beachhead, either opposed or unopposed.

In the first scenario, the force can be treated essentially as a CVBG (it may, in fact, include one.) Thus, the primary purpose of an SSN attached to it will be to protect the assets in the group using point defense ASW. If the forces deployed are to be used in a land attack and are smaller than a CVBG, they will likely include surface Tomahawk-firing assets. Most of the ships capable of firing these weapons also include some ASW capability24; they will not be completely helpless. Furthermore, their stay would not likely be protracted, if their mission was to perform a limited strike. Even if the National Command Authorities wished to hold the option of quick additional strikes in reserve, the force could easily withdraw from the coast to reduce any threat from local submarine or coastal defense forces. Still, it would not do to be successfully attacked by local conventional submarines. To that end, forces smaller than a CVBG would benefit from one or two SSN escorts; two when they close with a hostile coast, as they lack the surface and air assets of a CVBG; but for short missions, especially if U.S. intelligence assets are able to provide likely location of any enemy submarines, one SSN should be sufficient, supported by organic ASW helos.

As for amphibious or sealift resupply operations, there is a different requirement. In this case, the forces are not closing with a hostile coast to fire missiles and leave; rather, they will be securing, holding and utilizing a 'corridor' from the open oceans to the coastline. Vulnerable ships will be transiting this corridor on their way to and from the shore. In this case, ASW efforts will be area-based and vigorous in an attempt to keep these assets from harm. This provides two balanced driving factors. On one hand, the importance of the job and the larger size of the area to be protected would indicate more assets.

On the other hand, however, any surface combatant ASW capability would likely be employed at maximum effort during these operations. Friendly SSNs might succeed only in getting in the way if they were too close. Second, shallow water ASW was not a primary design requirement for modern U.S. SSNs, and it shows. The Los Angeles displaces between 6,927 and 7,177 tons when submerged, making it much larger than likely opposing diesel-electric boats, and the Seawolf will be larger, over 9,000 tons. In comparison, the Kilo class boat, a large conventional submarine, displaces 3,076 tons submerged.25 The Los Angeles is not as maneuverable as smaller conventional boats, making operations in shallow and constricted waters with many obstacles difficult. One of the design requirements of the Seawolf class, although not a primary one, is in fact improved shallow water operations.26 These are to come through better magnetic stealth and quieting and improved shallow water weaponry (a shallow ADCAP) rather than smaller size and maneuverability, however. A professional U.S. submarine designer has opined that the only thing that will give the U.S. increased littoral ASW in the submarine force is a new, smaller submarine.27

In any case, the bulk of our modern SSN force is not eminently suitable for littoral operations. As such, their most useful task in protecting Naval Expeditionary Forces would be to protect the ocean end of the transit corridor, and to patrol out from the coastline to eitther side of the corridor, several miles away. As the ocean end of any amphibious operation will doubtless be protected by at least a CVBG, which also would be providing air cover to the landings, its escorting SSNs and ASW assets can be counted on to secure the nearby ocean access. Two SSNs might be profitably employed to either side of the corridor to protect against enemy submarines hugging the coastline to avoid contact with blue-water USN forces. In addition, they would be situated to provide land attack capability through tube-launched or VLS Tomahawk weapons in support of the ongoing operation.

In both the above cases of Expeditionary Force escort, the SSNs employed (one for a strike group, two for an amphibious op) would only be deployed when the Force is generated. There would not be an ongoing requirement to keep these boats at sea. However, since the Navy is planning to be capable of deploying this type of force, a requirement of two deployed SSNs for this type of operation is reasonable. Additional at-sea units could be generated on an 'as needed' basis through increased operational tempo or other means, which I will discuss in the section on deployment ratios.

Shipping
The final escort mission sub-category is that of protecting U.S. or allied military or commercial shipping. Hypothetical examples might include protection of MPS ships enroute to a deployment, or of sealift assets enroute to the theater. Or, in the case of commercial shipping, U.S. forces might be called upon to protect ships travelling through dangerous waters; tankers through the Straits of Hormuz, or more likely allied ships entering a conflict zone.

I consider this an unlikely SSN mission. In the case of American military shipping, MPS ships would, if required, receive a destroyer and/or frigate escort designed to operate at sustained high speeds. Although an SSN can operate at high speeds submerged, the acoustic capabilities of submarines are dramatically reduced during speed runs. Thus, their utility for convoy protection would be limited. This is especially true in the case of the newer fast sealift assets of the U.S. military. Designed to cruise at a speed of 19 knots, they would be extremely difficult to keep up with, and any SSN that did so would be effectively useless as an ASW platform.

A more likely response would be to use the SSN in an ASW operation separate from the convoy, to sanitize dangerous areas through which the convoy would pass, and those operations fall more under the category of ASW missions, which are discussed below. As a result, I do not believe there is any requirement to generate boats for this sort of duty.

Escort Mission Category Totals
To sum up escort duties, then, we have a requirement of three boats for CVBG escort, and two boats for Naval Expeditionary Force escort, with the caveat that the latter will likely not be a continuous requirement, and may overlap with land attack requirements. Any of the boats in the current U.S. inventory, with the exception of the converted Special Ops boats, is capable of carrying out these missions; although for missions which overlap with Land Attack, the best asset would be a Los Angeles Flight II or Improved boat, both of which have external VLS cells for Tomahawk missile launches. The Seawolf will not have VLS capability, although it will be capable of tube-launching SLCMs. Whether or not the New Attack Submarine will incorporate VLS in the non-dedicated boat is still unclear. One variant of the SSXN, the SSLN, would be a dedicated land attack boat, but it is unlikely that such a boat would be suitable for escort duties. It is more likely to be an escorted asset itself. In any case, since 31 of the Los Angeles boats do have this capability, finding assets to carry out these missions should not be difficult.

Anti-submarine Warfare (ASW)

Antisubmarine warfare is the forte of the attack boat. In the case of modern submarines, it is what they were designed to do. The SSN is, according to some, the ASW asset of choice, as it does not have to cope with excessive noise as does a surface ship, and its endurance is essentially unlimited, unlike aircraft. It is better able to defend itself than a surface asset, as well.28 It is also the mission where technology and boat type can make the most difference, depending on the target. Currently deployed American attack submarines are quieter, in general, than any other attack submarine deployed with the possible exception of a small number of improved Akula-class Russian boats and an as yet unlaunched submarine being built at Severodvinsk, to be named for that city. This 'quietness gap' is continually trotted out in funding requests for the Seawolf and New Attack Submarine programs.29

There are several facts to bear in mind, however. One, the number of improved Akulas completed is quite small, between five and ten units.30 Second, the lead Severodvinsk has not even been launched as of yet, and given the economic turmoil in Russia, the possibilities of delays or even cancellation still exist, although the latter is unlikely. The second is that the Russian Navy, while a potential opponent, is not in our 'most likely scenario' list extrapolated from the strategy related documents examined so far.

For an examination of potential ASW missions, a number of possibilities exist, of varying likelihood. I will go over each possible ASW mission in turn.

SSBN Surveillance/Prosecution
Keeping track of ballistic missile submarines is a difficult process, and is most reliably accomplished by having attack submarines trail the SSBN as it leaves port, remaining with it 'on watch.' However, the wisdom of this strategy is in doubt, as any actions which make an enemy's strategic submarines vulnerable will also make him nervous. For these reasons, explored at length in Barry Posen's Inadvertent Escalation, especially Chs. 4 and 5, large-scale shadowing of enemy SSBNs would be an unwise strategy. On the other hand, I concede that it may be necessary to both keep track of enemy fleetwide SSBN activity (sailings and port calls) and to occasionally track enemy SSBNs for training purposes and more importantly to gather intelligence on their observed characteristics. If done in small enough scale, these operations would not present a threat to the force as a whole.

Therefore, although conflict with Russian SSBNs is not foreseen and would be a bad bet if it did occur, tracking, especially occasional tracking, of Russian SSBNs is desirable. More importantly, keeping track of the status of the Russian SSBN fleet by watching their operating bases is necessary insurance, even if they are not pursued after sailing. Jan Breemer offers maps of the major Russian operating bases; although it is clear that there are more bases than can be practically covered by U.S. SSNs, that is not important; one SSN 'watching' each fleet, North and Pacific, would provide adequate warning. These patrols could be augmented in time of heightened tension to gain a more complete picture of Russian SSBN deployments. According to the map, there is one major SSBN base in the Pacific, at Petropavlovsk, and all the North Fleet bases are along the Barents Sea coast, not very distant from each other. With three main SSBN bases, at Litsa Guba, Polyarnyy, and Gremikha, a single SSN patrolling along the coast would be able to keep track of any major fleet deployments.31

The Russian Navy is not the only non-NATO bloc fleet with SSBN's; the Chinese have one, although it is probably not worth keeping constant submarine eyes on. With one SSBN and 5 SSNs, the Chinese nuclear submarine fleet would be unable to maintain an operational tempo that is threatening to the United States; and given that she only has one SSBN, designed to deploy on 24-hour alert, any attempt to track it would probably induce extreme levels of nervousness.32

In toto, I will assign two SSNs to surveillance of SSBNs. These missions will show overlap with shadowing SSNS, since the Soviet SSN force is based alongside the SSBN force.

SSN Surveillance
This is a somewhat vaguer mission requirement. The Russian Navy has large numbers of SSNs, even after recent mass retirings. Surveillance of these boats would serve two purposes; first, it would be useful as noted for the SSBN task for garnering intelligence and observations of the various types of SSN which U.S. Navy might expect to face. Second, it is the primary method of training SSN crews. Submarines effectively operate on an 'at war' footing much of the time; tracking targets and evading detection are peformed exactly as they would be in time of conflict.

Although it sounds somewhat provocative, tracking other nations' SSNs is the best form of training the U.S. Navy can provide its crews in peacetime. This does not mean, however, that this should be a mission requiring continuous or even temporary dedicated deployments. Any boat, with time allotted to training, could engage in this activity. All of the other boat missions, in fact, will likely involve this sort of activity. The only time that specifically sending boats out to do this sort of thing might be worth it is if performance data on a new type of opposing SSN is needed, in which case, the deployment would be on an 'as needed' basis as opposed to a continuous deployment. And as mentioned above, this mission overlaps with SSBN surveillance; given the proximity of the two missions, there is little reason that the two boats allocated to that duty could not be detached to perform this one, although replacing them on the line would be wise in order to keep tabs on SSBN sailings.

For these reasons, I do not believe this mission generates any continuous deployment requirements.

ASW Area defense
I do not deal with point defense activities here, since they have been covered in the 'escort' section. Area ASW defense involves the attempt to detect and possibly eliminate all hostile submarine activity in a fixed geographical area, and to deny entry to other submarines. Depending on the level of conflict, denying entry might mean either denying undetected entry, or denying entry altogether.

This is the mission requirement in which it would be most useful to generate scenarios and discuss likelihoods. First, it is unlikely that the U.S. will seek to conduct lethal area defense against an adversary armed with SSNs. The only two realistic possibilities, Russia and China, would only occur in the context of a conflict far larger than the strategies we have examined so far. There is no reason that it cannot occur, however; but in that case, I believe that the operational tempo of the SSN force would be high enough to offer a sufficiently sized force, if not permanently then at least for the duration of a conflict. This is especially true in light of Russia's well-publicized problems with her nuclear submarine fleet, and the imminent shrinkage of the force due to age if no other opponent.33 Furthermore, multiple sources put Russian building rates at between one and six boats per year34 which, assuming a standard 30-year life cycle for a nuclear submarine indicates an eventual force size of between thirty and one hundred eighty high quality boats. The building figures really apear to be around two or three boats per year, indicating a force size of sixty to ninety. This is including SSBNs, however; a Russian admiral recently indicated that he 'hoped' to build between 1.5 and two non-SSBN nuclear submarines per year.35 This would lead to an SSN force of between 45 and 60.

Sinceit is unlikely that U.S. SSN production will cease, and that some follow-on to the Seawolf will be procured at a slower rate, perhaps .5 per year, U.S. submarine forces, while contracting, will not shrink to zero. in addition, they will maintain some level of acoustic advantage, although the magnitude of it is unclear. For more information, see appendix 2, which contains a chart of estimated relative noise levels of U.S. and Soviet/Russian designs.

By far the most interesting scenario to explore, therefore, is that of area defense against a third party conventional submarine force, which would pose some problems. The most popular scenario presently seems to be a Persian Gulf conflict involving Iranian submarines, as the Iranians have purchased at least two modern Kilo class diesel-electric boats from Russia and are known to be shopping for other naval assets.36

It is unlikely that the U.S. Navy would find itself attempting to sanitize more than one area of hostile submarine activity simultaneously. Even in the case of the 'two MRCs', given the fact that the MRCs in question are openly assumed to be Iraq and North Korea, there does not appear to be much of a problem. Iraq has no navy to speak of, and certainly no submarines. North Korea's forces consist of North Korean copies of Chinese copies of 1950's Soviet diesel-electric boats; these do not pose any real threat and could easily be handled by surface and air ASW assets, perhaps with minimal SSN assistance.

To return to our 'interesting' case, let us assume that the Iranian navy attempted to operate its submarines in the Persian Gulf and out into open water. Their most likely course of action, in the absence of a general conflict with the west, would be to utilize them to 'pick off' occasional tanker traffic or other cargo traffic, in order to assert control of the Gulf or to raise oil prices as in the 'tanker war.'37 There are two possible methods of deployment available to Iran, considering their geographical situation. The first is to send them out on actual patrols to hunt targets until their weapons are expended. This is a poor choice given the restricted waters of the Gulf and the concomitant vulnerability of submarines within. The second, more likely method would be what is known as 'Boghammar tactics'38 - to sortie their submarines to attack specific targets and immediately return to port.

In either case, it is not clear that SSNs would be the most effective method of dealing with this contingency. In the first instance, with U.S. forces' current access to the area and the previously mentioned physical restrictions on submarine operations within the Gulf, the most productive response would more likely be a massive air effort from bases in Saudi Arabia and/or from aircraft carrier platforms, perhaps coupled with a coordinated sweep by surface escort vessels with helo capability. This offers less risk of losing the expensive SSN asset that might not be that useful in those waters. The real danger level to U.S. SSNs operating in the Gulf would depend on what types of torpedo Iranian Kilos were using, their level of proficiency, and the degree of mining that Iran undertook. A number of nations produce advanced seeker torpoedos, from the U.S. Mk. 48 (which it is unlikely Iran would have) to the Russian and French equivalents. It is possible that Iran would have weapons with some seeker capability, and the Kilo is capable of firing wire-guided weapons.

In that case, the shallow and restricted waters of the Gulf would increase the danger, as there are no thermoclines to hide beneath or above; and maneuvering room is limited, especially for the larger SSN. The outcome of this scenario really depends on a great number of factors; suffice it to say that while there is no doubt that the U.S. Navy could deny Iranian submarines access to the Gulf, the cost of doing so is indeterminate.

If the Iranian SSs opt for Boghammar tactics, aggressive mining of Iranian submarine bases, SSNs 'lurking' near those bases, and escorting tankers with ASW assets would appear to be the most productive course.

The advantage of the SSN is its stealth, which is helpful both for survivability and for low political visibility. If the United States were to operate without assistance from neighboring nations, or in the face of regional hostility to U.S. action, surface escorts and land-based aircraft might not be feasible. In that case, perhaps two SSNs sent up the Gulf to both prosecute targets and mine Iranian ports with CAPTOR weapons would be the best solution. In neither case, however, would a prolonged deployment be required. I would allocate two boats for this purpose, possibly three. The scenario would not require continuously deployed boats, however, so no continuous boat deployments arise from this requirement.

ASW Totals
To sum up, then, for ASW related missions, only two boats would need to be continuously deployed, for SSBN and SSN surveillance of the Russian fleet. The other missions, ASW area defense and surveillance of other fleets, do not require continuously deployed boats; at maximum, ASW area defense might require three to four boats on a temporary basis.

Anti-surface Warfare (ASuW)

The original attack mission of the submarine was to destroy surface vessels, either combatants or commerce. In World War II, submarines were employed with best effect against enemy merchant marine, firing at combatant escort vessels only in self-defense or when attacking convoys with large torpedo spreads. After that war, the nuclear submarine evolved into a specialized ASW asset. This is not to say, however, that SSNs have decreased ASuW capability. The British submarine HMS Conqueror demonstrated this by sinking the Argintinian cruiser General Belgrano at the outset of the Falkland Islands war. Above, when examining the current U.S. inventory, I noted that the large majority of current U.S. boats carry not only torpedo weapons but sea-skimming Harpoon missiles designed for surface attack as well as the capability to carry Tomahawk anti-ship missiles, with a 250nm range.

Continue to ---> The Back of the Envelope: Part II

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