The U.S. is watching North Korea for signs of military action.

U.S. officials say that North Korea could take military action against South Korea in the coming months. The officials think that Mr. Kim has been more aggressive in his statements than in the past and should be taken seriously. The officials said that they did not believe there was an imminent risk of a full-scale war on the Korean Peninsula. The shelling of a South Korean island by North Korea in 2010 was an example.