A false flag operation is a type of covert operation made to appear as though it is being carried out or sponsored by a party other than the actual acting or sponsoring party. The term "false flag" is derived from the military tactic of flying false colors, i.e. flying the flag of a country other than one's own. Typically, the deception of being sponsored by a different party than the actual one can be created through, amongst other methods, the use of the other party's flag, uniform, insignia, identifying signal, or equipment.

Flying a false flag is an old, much-used tactic, and one that is seen often even in the schoolyard with children playing Capture the Flag:
Child #1: "Catch him! He's running onto our side, trying to grab the flag!"
Child #2: "No, I'm on your team!"
Child #1: "Oh." Child #1 looks away.
Child #2: "NOT!" Child #2 starts running, grabs flag and runs back to his own team's side.

Two simple methods of foiling a false flag operation in Capture the Flag are to memorize who is on each team, or to tag the other kid anyways just to be sure, or both. In an actual battle, however, this cannot be done: the first action is not possible given the size of and lack of communication in most nation's armed forces and the combat equivalent of the second action would result in friendly casualties.

In general warfare and the legal proceedings following such warfare, the false flag has become accepted as a method of deception, so long as the deception is dropped prior to engaging in battle, a use of the tactic that is specifically prohibited as a crime of perfidy. It is also prohibited to pretend to be a party that is neutral to or not involved in the conflict.

False flag operations can serve several purposes:

  • Prevention of attack: A group of soldiers disguised as the enemy might be able to move through enemy territory without being attacked.
  • Gaining a strategic advantage while attacking: In actual battle, if two groups of soldiers are dressed in the same uniforms, when one group fires on the other, the other group might think the other is mistaken and not fire back. Even if this doesn't happen, there will probably be confusion that will take precious time to sort out.
  • Gaining a strategic advantage while being attacked: In a battle, if a group of soldiers begins firing on another group of soldiers and the attacked begin to scream that they are all on the same side, the attackers might cease firing or become confused.
  • Deniability: A false flag operation, if successful, will allow a party to get away with doing something that it wouldn't normally. Also, should a clandestine or covert operation be discovered, deniability can still be salvaged if it has been run as a false flag operation and it appears that another party is responsible. This purpose is also sometimes combined with framing, described below. This purpose is commonly associated with black operations.
  • Framing: A false flag operation can be used to perpetrate an act and then blame that act on another party, commonly in order to justify action against the framed party or turn popular opinion against the framed party. This goes hand-in-hand with the deniability purpose described above, as doing something bad that you wanted to do and then blaming it on someone else is another old strategy and one that can be used to kill two birds with one stone. The German Nazis are well-known to have made use of framing through false flag operations, one instance being staging, helping along, or not stopping (depending who you ask) the Reichstag fire incident in order to get President von Hindenburg to sign the Reichstag Decree, suspending an enormous amount of freedoms for German citizens. Another good example is the Gleiwitz incident in 1939, in which Germany created false evidence of a non-existent Polish attack to justify war on Poland, starting World War II in Europe. Of course, the USA (or pretty much any other nation) is not innocent of such scheming: the Kennedy administration developed the never-enacted Operation Northwoods, which was planned to spark a war with Cuba.
  • Discovering secrets: A false flag operation can be used as a method of infiltration in order to gain intelligence meant for the enemy. Undercover cops and spies both commonly employ this technique, in order to infiltrate the enemy ranks as well as, when posing as spies for the enemy to test their own ranks for loyalty. Earl Edwin Pitts, an FBI agent spying for the Russians was caught when he responded to FBI agents pretending to be Russian agents. Often, this sort of use on civilians runs very close to entrapment, although it is generally not an issue legally when dealing with international affairs.

Although false flag operations are often associated with direct action, specifically open warfare, very often this is not the case, because the restrictions of international laws on the use of false flag tactics during warfare do not allow for the use of these tactics to their full strategic advantage. More often false flag tactics are used in intelligence, indirect action operations, and black operations because there are no such legal restrictions either in existence or being obeyed.

In modern context, perhaps the most famous example of false flag operations is that of many 9/11 conspiracy theories, which largely center around the belief that the attacks on the World Trade Center were permitted, staged, or allowed by the US government in order to start the wars in Afghanistan and/or Iraq. Although I personally don't believe these theories, bear in mind the examples I have given (which are only a few of the many that have been documented, not to mention the ones that have never been uncovered) above when you weigh the possibility of the truth of these conspiracy theories for yourself. Many governments, including the USA, in fact, have staged or considered staging similiar false flag operations before, with world-changing effects. Rather chilling, no?