WASHINGTON (Reuters) - U.S. Senate Democratic leader Chuck Schumer said on Tuesday that President Donald Trump s characterization of North Korean leader Kim Jong Un as  Rocket Man  during a speech to the United Nations was  risky.   If I were giving the president advice, I would have said avoid using  Rocket Man,  Schumer said during a press conference at the U.S. Capitol.  We know the leader of North Korea is erratic, to put it kindly. That kind of language I think is risky.  