Beaten to it - rightfully - by legbagede. A hearty 'me too' for his excellent writeup above. Although, dude, footnotes within footnotes? Who are you trying to be, here, David Foster Wallace?
I feel compelled to chime in here. I'd like to look at each of the three statements made by stewacide in the above post that concern the named states.
Iraq. Contrary to what is written, Iraq does in fact have a relatively strong military capability - especially compared to Afghanistan. Although not in control of the airspace over a good portion of their state, the Iraqi armed forces retain a large portion of the equipment and formations that they had in The Gulf War. After-action analyses done by Coalition nations (the U.S. most specifically) indicated that the claims of armor destroyed were in fact quite high relative to the verified kills (verified by walking up to them after the ground war had begun). Some large units, including Republican Guard units, were never even engaged by ground forces during the Gulf War because Saddam Hussein chose to hold them north of Baghdad and the Coalition advance. As for potential WMD threats, Richard Butler (ex-head of the U.N. Inspection team) states quite clearly in his writings that in his opinion, the Iraqi weapons development program cannot be considered neutralized without on-site verification. There is considerable debate as to the amount of program infrastructure actually destroyed by U.N. inspection teams, given the draconian limitations placed on their movements inside Iraq.
While the Iraqi military may not be the behemoth (regionally speaking) that it once was, there is no reason to doubt (especially given the resource allocation patterns made obvious by Hussein's government) that there is a solid core of combat-capable units in the Iraqi armed forces, which remain under tight command. Look at it one way: In all the instances of exchanges of anti-aircraft and air-to-ground fire over the no-fly zones, exactly zero Coalition aircraft have been lost. Many Iraqi air-defense crew have been killed. Yet they keep trying; this implies fairly good discipline or lots of fear. Both indicate that Saddam Hussein remains firmly in control of the military arm, and that he has no problem losing (fairly expensive) radars/launchers to U.S. counterstrikes.
Finally, comparing the Ba'ath regime to the Taliban is misleading. The Ba'ath have been in power and consolidating their grip for decades, where the Taliban were relative newcomers. The Iraqi regime has a much more established infrastructure in terms of military and political linkages (the Taliban didn't really even have a formal military; it's just that their opponents were in an even worse state). All this prompts me to disagree with the assessment that Iraq's government could be dealth with using the Afghanistan recipe. One final note: whatever they say about him, Arab nations acknowledge Hussein as the current lawful government of Iraq, as does everyone else, including the United States (we acknowledge he is; we just don't like it). Trying to destabilize and overthrow an established Arabic government is a far cry from smacking down a sectarian government that even other Muslim regimes really wanted nothing to do with and saw primarily as a useful dumping ground for their own domestic malcontents. The reaction from the Arab world would be strong; even while fighting a war against Iraq, the U.S. had to perform delicate coalition management (i.e. compromise) to avoid local nations getting the image of the U.S. destroying a local Arab leader. In this case, even our NATO allies have been making strongly worded arguments as to why Little Bush's speech was a dumb move.
Iran. This case is admittedly murkier; however, I would point out that given the Ayatollahs demonstrated ability to (and habit of) dismissing and/or incarcerating opponents from the secular government, I am hard pressed to see these reforms as progressing in any meaningful sense. I will acknowledge encouraging signs from Iranian citizenry and the secular government; however, I don't believe those were the target of Little Bush's speech.
North Korea. Nations that 'can't even feed their own people' and yet have the ability to manufacture (and, likely, existing stockpiles of) weapons of mass destruction, coupled with long-range missile technology, are far more dangerous than nations which have weapons and missiles and can feed their people. Eventually, the government may decide that the people are a present danger to them. At this point, the phrase 'Nothing to Lose' becomes frightfully applicable.
Turn the question around. What if the North Korean government, which we all acknowledge does an unfortunately good job of informational control within its borders, simply announced to the West that their situation was untenable? They might demand that the West provide them with vast quantities of aid, or else they would feel no qualms about firing several of said missiles against the Japanese islands. While it's easy to say 'what could they do?' remember that the option on the other side of the coin is for either the U.S. to actually conventionally strike North Korea or for the U.S. to take the brinkmanship position of priming its own missiles in response. If the North Korean government feels that they have perhaps seven days before a starving mob drags them from their palaces and shoots them in the street, how do you deter them?
I don't mean to imply that I support Mr. Bush. On the contrary, I think the speech was probably the most damaging bit of rhetoric to American foreign relations since great-granddaddy Reagan's 'We begin bombing in five minutes' gaffe. I don't believe there is an alliance between these states; far from it. I don't think he should have identified them by nation. However, I would be forced to agree that the current situations and regimes extant in those three countries do represent much of the probable direct threat to United States security (I won't claim the West's, or the world's) in the next couple of years.
To stewacide: Fair point ref. Iraq. I think I should be clear about what context I'm referring to when I speak of the 'strength' of the current regime. I don't have much to say on the current state of mind of the Iraqi populace; I also don't know to what degree units are being equipped and trained. Against a determined external assault by the U.S. et. el, this is a whole different story. However, given a) firm control of the military, b) lack of a credible organized armed resistance (the Kurds just don't count, for me, as a national resistance or an 'army') for the U.S. to proxy-fight through, and c) evident ample supply and presence on the part of the military (if not all of it, enough) I'd say that Iraq's regime is fairly safe. They've shown no hesitation to use any means available to subdue rebelious areas, and are still there.
Iran - I'm intentionally staying mum; I don't have good info on internal Iranian politics and views. I will just say, however, that we have not yet seen an issue where the secular government even took a successful stand against the religious orders; but several instances of unsuccessful ones.