Kim said the deal between Seoul and Washington was an “offensive act severely violating [Pyongyang’s] security and maritime sovereignty and a threat to security that must be countered”, according to state news outlet KCNA.
It was now urgent to “further accelerate the radical development of the modernisation and nuclear weaponisation of the naval force” of North Korea, Kim added, according to the report.
Kim made the remarks as he toured a facility on Wednesday where Pyongyang is working on an “8,700-tonnage nuclear-powered strategic guided missile submarine”.
The North Korean leader on Wednesday also oversaw the test firing of a new high-altitude long-range anti-air missile into the Sea of Japan, according to KCNA, which the news outlet referred to as the “East Sea of Korea”.
KCNA reported that the test was successful, and the missile successfully hit a mock target at an altitude of 200 kilometres (124 miles).
The developments came as Seoul said it was pursuing a “standalone deal” with the US to acquire nuclear-powered submarine technology, according to South Korea’s Yonhap news agency.
US law bans the transfer of nuclear material for military use, but South Korea could receive an exemption from US President Donald Trump, the East Asian country’s national security adviser, Wi Sung-lac, told the media following a meeting with Secretary of State Marco Rubio and Secretary of Energy Chris Wright.