North Korean leader Kim Jong Un called for bolstering nuclear forces this year during a visit to the country's nuclear material production base and nuclear weapons institute, state media KCNA said on Wednesday.

The dictator, eager to shut out the influence of Hollywood and K-pop, has been exalting a “shock brigade” of 300,000 teens and 20-somethings drafted into flood reconstruction.

South Korea 's Yonhap News Agency said North Korea might be using a vertical cold-launch system to fire the missiles. The system, which is commonly associated with submarine- and ship-based weapons, ejects a missile from its container before the missile ignites midair.

U.S. President Donald Trump said in an interview broadcast on Thursday that he plans to seek to engage North Korean leader Kim Jong Un anew after the two men developed a working relationship in Trump's first term.

North Korea has test-fired sea-to-surface strategic cruise guided missiles, the North's state media reported Sunday, quoting Kim as saying that Pyongyang's deterrence means are being perfected.