In his 1933 inagural address, FDR said, "So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself -- nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance." In the panic of 9/11, given George Bush's famous facility with language, it should not have surprised us that he would examine history and come to the conclusion that the real enemy is Terror itself (I'm reminded of the scene in the movie, "The Jerk," where Steve Martin's character cries out, "Stay away from the cans!") Thus, for the first time in our history we have sent troops abroad to wage a war against an emotion.
As a logical extension, if we can operate a shooting war against one emotion, why not all of them? After all, Terror is not the only emotion our enemies are trying to export. Even some of our so-called allies would have us experience "Love" and "Peaceful Safety" - and it's clear that if we don't oppose these feelings abroad we will soon have to fight them here at home.
What other emotions should generate a military response?