The United States said Wednesday North Korea's lethal artillery strike on a South Korean island was premeditated and a violation of the 1953 Korean War armistice. But U.S. officials do not believe Pyongyang is preparing for an extended military campaign. State Department Spokesman P.J. Crowley told reporters the United States is engaged in wide-ranging diplomacy with China and others in the aftermath of the artillery clash, and intends to raise the matter directly with North Korea in the armistice framework.