North Korean leader Kim Jong Un “will lose sleep” over the prospect of South Korea deploying a nuclear-powered submarine, Seoul’s defense minister said Sunday, forecasting that construction could finish within the next decade.

ROK defense minister Ahn Gyu-back made the remarks during an interview with national broadcaster KBS, discussing the Lee Jae-myung administration’s plans to develop nuclear-powered vessels and ongoing preparations to assume wartime operational control (OPCON) from Washington by 2030.