A retaliatory strike is a warning or revenge act usually taken by a government. It is claimed in the regime's or militant group's own propaganda to be a response to some immediately prior action by "the other side".
However, this logic suffers from a serious subject-object problem:
- it is not always clear who is "responsible" (note the common root with "response", those "responsible" are literally "those whom one can get away with responding on")
- even if it is, the so-called retaliation does not always even pretend to target those with the most direct links to them, but rather, is usually a pre-chosen target of convenience, often chosen in advance for diplomatic or military significance to a very broad concept of "the enemy" or "the other" who is attacked
- claims that one is entitled to strike back are thus inoperative - it is not those who are striking who are struck at, necessarily, and other than timing and some vague perception of alliance on the part of the attacker, there is often no connection between two attacks - which are only connected by the propaganda itself.
One example is the unique conception of Israel, homeland defense which permits it to occupy foreign territory for generations, settle its own citizens there in defiance of international law, and when suicide bombings result, to attack sovereign states which it claims are "supporting" the colonized people who resist and attack Israeli citizens. These strikes, it claims, are "retaliations".
The Bush Doctrine seems also to rely heavily on this same logic. There is no evidence whatsoever that Saddam Hussein had anything to do with the September 11, 2001 attacks on the US, but it was useful to Bush (whose agenda inherited from Project for the New American Century included pre-emptive attacks on Iraq and other states) to spread the idea that there were links between him and Al Qaida, and the disinformation that he had weapons of mass destruction that might be provided to them. However, this was not enough - it was also necessary to spread the fiction that Saddam Hussein was somehow involved directly in the 2001 attacks, to make the 2003 invasion of Iraq appear to be a retaliatory strike.
In effect, the broader the concept of a retaliation one accepts, the more power one has given a regime to attack literally any target that it finds convenient.