Pyongyang regularly criticizes such drills as rehearsals for invasion and sometimes responds with weapons tests, but Seoul and Washington say they are purely defensive.

North Korean leader Kim Jong Un said a U.S.-South Korea joint military exercise could "ignite a war" and called for the rapid expansion of Pyongyang's nuclear capabilities.

SEOUL, South Korea (AP) — North Korean leader Kim Jong Un condemned South Korean-U.S. military drills and vowed a rapid expansion of his nuclear forces to counter rivals, state media said Tuesday, as he inspected his most advanced warship being fitted with nuclear-capable systems.