RE: Pelosi: Bush lacks authority to invade

I actually agree with Pelosi on this one. I would consider a full-blown invasion to be an act of war, something Congress has to declare (even if they only sort of doing nowadays). If it's some limited incursion into Iran to go after Iranians backing Iraqi insurgents I think the President could constitutionally do that. It would be similar to him ordering limited air strikes to wipe out Iran's nuclear weapons program. For something limited like that I don't think Congressional approval is necessary.