North Korean state media warned on Tuesday of a nuclear attack on the United States at any sign of American aggression as a U.S. Navy strike group steamed toward the western Pacific.

U.S. President Donald Trump, who has urged China to do more to rein in its impoverished neighbor, said in a tweet that North Korea was "looking for trouble" and the United States would "solve the problem" with or without China's help.

Tension has escalated sharply on the Korean Peninsula amid concerns that reclusive North Korea may soon conduct a sixth nuclear test and after Washington said over the weekend it was diverting U.S. Navy strike group Carl Vinson from port calls to Australia toward the Korean Peninsula as a show of force.