North Korea said on Thursday it successfully launched ballistic missiles from a train for the first time and was continuing to bolster its defences, after the two Koreas test-fired missiles hours apart in duelling displays of military might.

Wednesday’s launches underscored a return of tensions between the rivals amid a prolonged stalemate in US-led talks aimed at stripping North Korea of its nuclear weapons programme.

Pyongyang’s official Korean Central News Agency said the missiles were launched during a drill of a “railway-borne missile regiment” that transported the weapons system along rail tracks in the country’s mountainous central region and accurately struck a sea target 800 kilometers (500 miles) away.

Rail based system

State media showed what appeared to be two different missiles streaking up from rail-car launchers engulfed in orange flames along tracks surrounded by dense forest.

A rail-based ballistic system reflects North Korea’s efforts to diversify its launch systems, which now includes vehicles and ground launch pads and may eventually include submarines. Firing a missile from a train could add mobility since North Korea has a railway network across the country, but its simple rail networks could also become easy targets during a crisis.

The South Korean and Japanese militaries said earlier that North Korea’s two short-range ballistic missiles landed inside Japan’s exclusive economic zone but outside its territorial waters. The last time a North Korean missile landed inside that zone was in October 2019.

Pak Jong Chon, a senior North Korean official who has been seen as influential in the country’s missile development, said Wednesday’s tests were successfully conducted in line with the “strategic and tactical design and intention” of the North’s ruling Workers’ Party.

Bolster weapon stock

North Korean leader Kim Jong Un vowed at a party congress in January to bolster nuclear deterrent in the face of US-led sanctions and issued a long wish list of sophisticated weaponry, including longer-range intercontinental ballistic missiles, nuclear-powered submarines, spy satellites and tactical nuclear arms.

In another weapons display over the weekend, the North said it tested new cruise missiles, which it intends to make nuclear-capable, that can strike targets 1,500 kilometers (932 miles) away, a distance putting all Japan and US military installations there within reach.

South Korea tests

Hours after the latest North Korean launches, South Korea reported its first test of a submarine-launched ballistic missile. As President Moon and other top officials watched, the missile flew from a submarine and hit a designated target, Moon’s office said. It did not say how far the weapon flew.

Kim Yo Jong, the powerful sister of the North Korean leader, criticised Moon and threatened a “complete destruction” of bilateral relations over the comments he made while observing the tests.

South Korea, which doesn’t have nuclear weapons and instead is protected by the US, has been accelerating efforts to build up its conventional arms, including developing more powerful missiles. Moon, while observing Wednesday’s tests, said the South’s growing conventional missile capacities will serve as a “sure deterrence” against North Korean provocation.

Kim Yo Jong took offence to Moon describing North Korean weapons demonstrations as a provocation and warned of dire consequences in inter-Korean relations if he continued with what she described as slander of North Korea.

She said North Korea is developing its military capabilities for self-defence without targeting a specific country, and that South Korea is also increasing its military capabilities. North Korea has often accused the South of hypocrisy for introducing modern weapons while calling for talks on easing tensions between the divided countries.

Short-range weapons

Kim Dong-yub, a professor at the University of North Korean Studies in Seoul, said the North Korean photos indicated the rail-fired missiles were a solid-fuel, short-range weapon the North first tested from truck launchers in 2019.

The missiles, likely modelled on Russia’s Iskander missiles, are designed to fly at relatively low altitudes where the air is dense enough to allow for manoeuvrability in flight, making interception by missile defence systems more difficult.

While the North is trying to broaden its launch systems, the analyst Kim questioned whether rail-mobile missiles would meaningfully improve the country’s military capabilities when the North’s simple rail networks would be easy targets during crisis.

Economic sanctions

Experts say North Korea is building up its weapons systems to apply pressure on the United States in the hopes of winning relief from economic sanctions aimed at forcing the North to abandon its nuclear arsenal. US-led talks on the issue have been stalled for more than two years.

Kim Jong Un’s government has so far rejected the Biden administration’s overtures for dialogue, demanding that Washington abandon what it calls “hostile” policies first. But North Korea has maintained its self-imposed moratorium on nuclear and long-range missile tests, a sign that it may not want to completely scuttle the possibility of reopening the talks.

Observers say Moon’s government, which has been actively pursuing reconciliation with North Korea, may have taken action to appear tougher in response to criticism that it’s too soft on the North.

The rival nations are still technically in a state of war since the 1950-53 Korean War, which pitted the North and ally China against the South and US-led UN forces, ended in an armistice, not a peace treaty.