North Korean ruler Kim Jong Un said a new naval destroyer was damaged in a "serious accident and criminal act caused by absolute carelessness."

Kim has framed the arms buildup as a response to perceived threats from the United States and its allies in Asia, who have been expanding joint military exercises amid rising tensions over the North’s nuclear program. He says the acquisition of a nuclear-powered submarine would be his next big step in strengthening his navy.

Kim promised to punish those responsible for the “catastrophic failure” after the naval vessel partially capsized during a ceremony attended by the leader.