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.

North Korea’s newest warship was severely damaged during a launch ceremony Wednesday, with leader Kim Jong Un, who witnessed the accident, saying it brought shame to the nation’s prestige and vowing to punish those found responsible,