North Korea test-fired two strategic long-range cruise missiles, state media reported Monday, hailing the exercise as a show of "combat readiness" against foreign threats.
Leader Kim Jong Un oversaw the drill -- staged Sunday over the Yellow Sea to the west of the Korean peninsula -- and called for "unlimited and sustained" development of his nuclear weapons forces, the state-run Korean Central News Agency said.
The goal of the exercise was to review the "counter-offensive response posture and combat capability of long-range missile sub-units," KCNA said.
The missiles flew for more than two hours, state media said, sharing photos of the missiles being fired and hitting a target.
Seoul's Joint Chiefs of Staff said the missiles were fired Sunday at 8:00 am (2300 GMT Saturday) from the Sunan area near the capital Pyongyang.
Kim vowed Pyongyang "would as ever devote all their efforts to the unlimited and sustained development of the state nuclear combat force", KCNA said.
North Korea last staged a ballistic missile test in early November, around a week after US President Donald Trump -- on a tour of the region -- expressed interest in meeting with Kim.
Pyongyang did not respond to the offer.
At that time, Trump had just approved South Korean plans to build a nuclear-powered submarine.
Last week Pyongyang showed off a nuclear submarine of its own.
Photos published by KCNA showed Kim walking alongside a purportedly 8,700-tonne submarine at an indoor assembly site, surrounded by officials and his daughter Kim Ju Ae.
Pyongyang viewed Seoul developing nuclear subs as "an offensive act severely violating its security and maritime sovereignty", Kim said, according to KCNA.
North Korean state media last week also published a defence ministry statement condemning the docking of the US Navy's nuclear-powered attack submarine USS Greenville in South Korea's Busan.
The cruise missile launch drill was aimed at countering these moves, said Yang Moo-jin, former president of the University of North Korean Studies in Seoul.
"The arrow-type cruise missiles, with a range of around 2,000 kilometres, are capable of striking not only the entire Korean peninsula but also rear bases of US forces stationed in Japan," Yang told AFP.