WASHINGTON (Reuters) -U.S. President Donald Trump has called off efforts to reach a diplomatic agreement with Venezuela and told his special envoy Richard Grenell to stop all outreach, a senior U.S. official said on Monday. The news, which was first reported by the New York Times, follows a series of military strikes on vessels carrying drugs near Venezuela. Trump told Congress that the U.S. is engaged in "a non-international armed conflict" with drug cartels.