Exactly as defined in the US Constitution. I wouldn't call the duties of the President, as defined in our Constitution, those of a leader. The PResident leads the armed forces & executive branch of our govt, yes, but he doesn;t really lead teh American people, at least not in my opinion, no matter who he is. IN times of emergency, like 911, or the Civil War, he can be a cerntral point of rallying and energy, but thats about it. Ultimately, we are responsoble for our own fate.
Also, the President can't just go around making war. There are checks & balances. They were adhered to in going to war on Iraq, I believe. Otherwise, why is Congress continually funding this war? -akhilesh