North Korean leader Kim Jong Un has vowed to equip his navy with nuclear weapons and build larger warships, in a move that underscores Pyongyang’s drive to expand its military capabilities despite heavy international sanctions.

State media said Kim made the announcement on Tuesday at the commissioning of the 5,000-tonne warship Choe Hyon in the western port city of Nampho, describing the nuclear arming of the fleet as a “strategic course” to keep the country’s forces ready for “multifaceted and efficient operation”.

North Korea says the Choe Hyon is fitted with some of its “most powerful weapons”, and Kim has already overseen a cruise missile test from the vessel. He also pledged to soon commission another large destroyer, the Kang Kon, and to begin launching 10,000-tonne-class “strategic warships” – a size that would symbolically narrow the gap with South Korea’s navy and bring the North closer to US and South Korean blue-water capabilities.

Pyongyang, which calls itself an “irreversible” nuclear state, frames the build-up as deterrence against Washington and Seoul. The Korean Peninsula remains technically at war, and Kim has accused the allies of driving the region “to the brink of a nuclear war”.