Congress has given the Commander-in-Chief the legal authority to use the armed forces in any manner necessary to pursue terrorists wherever they may be. It may or may not be necessary to declare war on any nation to do this. That's strictly a strategic decision that will be made at the appropriate time, and by Congress.
Respectfully, your answer is a dodge.
Regardless of the Constitutional matter of issuing a formal Declaration Of War, do you honestly believe that the US should attempt to prosecute war (by any other name) against 37 different countries at once?
Please couch your response with examples from military history where regular military echelons attacked in 37 different directions at once, and actually succeeded.
The constitution isn't a document you can disregard simply because it is inconvenient. There is only one body that can declare war and there is nothing in it that says Congress or the President can make war to circumvent some international rules which we are not subject to.
The Constitution is the supreme law of the land. War is war. When you send a soldier anywhere you are making war. And the only body that can authorize that is Congress.
Screw international "rules." There's the constitution or nothing.