North Korea has issued a sharp rebuke over the major military exercise being carried out by the U.S. and its South Korean ally, labeling the training a "war rehearsal." Newsweek reached out to the Pentagon and the South Korean embassy in the U.

Yonhap, a South Korean news agency, said this was the first time Pyongyang had publicly disclosed the construction of such a vessel. In 2021, Kim pledged to introduce a nuclear-power submarine in response to what he called escalating military threats from the U.S., and Washington will no doubt be concerned about the development.