The past has shown that the USA president (any of them) feels free to launch a limited military strike anywhere in the world that he wants to without prior consultation with Congress or the public. Surprise has to be achieved on the target, after all, for maximum effectiveness! ;-) (ask the Japanese and Germans about that) You can't have surprise when you talk about it beforehand to the public or Congress or deliver an official declaration of war beforehand to the upcoming recipient of the strike.

Therefore I tend to agree with Peter that Bush could easily decide to launch a limited strike of some kind on Iranian nuclear facilities....or the Israelis could do it...or the Israelis could do it and the Americans could give them some support.

All kinds of possibilities.

Look, Clinton did it more than once. Reagan did it. It happened in the Kennedy administration at the Bay of Pigs. Johnson did it. Nixon did it. None of them declared war on anyone. None of them got impeached for it. Nixon got in lots of legal trouble eventually, yes, but over Watergate, not over illegally attacking foreign countries.