Despite following all the news, I still don't understand how one fights a war on an "ism"
In this case, terrorism. Is it a declared war? Does it permit invading another country? How is the specific terrorist country picked? How many countries will we have to invade before the "war" on "ism" is over?

Tried to find a good definition.

Terrorism n. A. method of keeping political control by means causing fear among the people governed; also, political opposition using means planned to cause fear among the persons governing.

Now, what's going on in Iraq doesn't quite fit the definition. Unless . . .