North Korean leader Kim Jong-un has slammed joint military exercises among South Korea, the U.S. and Japan as he called the leaders of the three nations “gang bosses.”

According to the North’s state Korean Central News Agency on Tuesday, Kim made the remarks in his celebratory Navy Day speech on Monday at the Naval Command of the Korean People’s Army.

The leader blasted a meeting of the three countries’ “gang bosses” where they announced regular trilateral military exercises, directing apparent criticism at the recent Camp David summit while referring to South Korea as the “Republic of Korea” for the first time.

Kim reportedly said that the waters of the Korean Peninsula have become the most unstable around the world with the danger of nuclear war due to the reckless confrontational maneuvers by the U.S. and hostile forces.

He added that the current situation requires the Navy to maintain war readiness and a constant combat alertness.

Kim was accompanied by his daughter Ju-ae during the visit, her first public appearance with Kim in about 100 days since May 16 when Kim conducted an on-site inspection of a preparatory committee on the North's attempt to launch a military spy satellite.