North Korea's Kim calls for strengthening naval forces

North Korean leader Kim Jong Un has called for strengthening the country's naval forces, accusing the US of turning waters near the Korean peninsula into "the most unstable waters with the danger of a nuclear war," state media KCNA reported on Tuesday.

In a speech to mark Navy Day, Kim said the "gang bosses" of the US, Japan and South Korea announced regular joint military exercises, KCNA reported, apparently referring to their Aug 18 summit at Camp David, Maryland.

In the first standalone meeting between the leaders of the US, South Korea and Japan, the three agreed to deepen military and economic cooperation as they seek to project unity in the face of China's growing power and the North's nuclear threats.

"Owing to the reckless confrontational moves of the US and other hostile forces, the waters off the Korean Peninsula have been reduced into the world's biggest war hardware concentration spot, the most unstable waters with the danger of a nuclear war," Kim was quoted as saying.

South Korea and the US last week began the Ulchi Freedom Shield summer exercises, designed to enhance their joint responses to North Korea's nuclear and missile threats. Pyongyang has long denounced the drills as a rehearsal for war.

Kim said North Korea requires its Navy to maintain war readiness, a "constant combat alertness," and called for "radically" modernising its weapons and equipment.

"He stressed that the navy of the DPRK would become a component of the state nuclear deterrence carrying out the strategic duty," KCNA reported.