WASHINGTON (Reuters) - U.S. President Donald Trump met on Tuesday with his top defense officials for a briefing and discussion on options to respond to any North Korean aggression or if necessary to prevent Pyongyang from threatening the United States and its allies with nuclear weapons, the White House said in a statement. Trump was briefed by Secretary of Defense James Mattis and Chairman of the Joint Chiefs of Staff General Joseph Dunford at a meeting of members of his national security team, the statement said. 