Don't make me laugh. You forgot one thing -- the US heavily funded the creation of the terror network Bin Laden now heads. If it turns out he was involved, should we declare war on America too? or are we going to only attack countries full of brown people?
We declare war on the countries that issued the passports of the hijackers. If that means we declare war on countries we had thought were our allies, such as Egypt and Saudi Arabia, then so be it.
War is hell because it is.