Entirely ignorant of the law and rule regarding war, eh?
There are no constitutional or other US law conditions, or judicial restraints to the government declaring war, it is a congressional function, not reviewable by the courts, with no burden proof involved. In this case a declaration would be superfluous anyway, since the terrorists have begun to wage war, without declaration (war begins with the first hostilities, if before declaration). Their actions is all of : waging war; piracy (private persons waging war against a government other than their own); war crime (atrocity); other international, national, and local crimes. Recall the Dec 8 1941 resolution by Congress, it was not a declaration of war, but a statement that war had begun a the time of the Pearl Harbor attack, rather than some hours later when the Japanese declaration was delivered. In response we can wage war (no proof or any judicial hearing involved, nor even review possible by courts) and proceed to investigate and prosecute any of the various crimes, without any obligation to pick among the two course; we may do both. We capture a member of one of the targeted organizations, and cannot proof anything against him individually, we may hold his as a POW, no trial, while the conflict goes on. No warrants are needs for military or intelligence actions against the enemies. Any one we can prove a specific crime against, try him and jail him as criminal, pirate, or war criminal. Any nations that allow them in their territory, give them the notice and time limit pertain to neutrals who have belligerents in their territory. If they do not expel or intern them, they sacrifice neutrality and a now belligerents. The terrorists have the worst of both legal worlds, belligerency & criminal. They do not have a legal pot to piss in.
