“If I’m president, the Iranians will have no question, but that I will be willing to take military action if necessary to prevent them from becoming a nuclear threat to the world. I don’t believe at this stage therefore, if I’m president, that we need to have war powers approval or a special authorization for military force. The president has that capacity now.”
The Constitution does not grant the President the power to unilaterally launch war. The President does have latitude to respond without congressional approval if we are attacked.
He is correct, however, that apparently our President “has that capacity now.” He has the capacity, not because it is constitutional, but because our Congress is spineless and more worried about getting re-elected (i.e., blaming these controversial decisions on the sitting President). See reason.tv’s great video about the history of this disturbing power shift.