I don't think you can do that. You can't recognize a government 'after the fact' and declare war on them. There's probably some law out there. But a country has the right to defend themselves, and if there is some certainty that some people, gov't, etc. attacked another people, country, etc., well, I guess you can do anything you wish. UN approval is good, but I think the world condemns these acts and if we play the diplomacy card right, 'declaring war' isn't a necessity. We haven't done it since WWII, so what's the difference now?