North Korea test-fired what appeared to be a submarine-launched ballistic missile into the East Sea, the Joint Chiefs of Staff said Tuesday, as South Korea, the US and Japan step up efforts to bring Pyongyang back to nuclear talks.

“We’re closely monitoring the situation and maintaining our readiness,” the JCS said, adding that South Korean and US intelligence were analyzing the launch, which took place at Sinpo, a port city along the east coast where North Korea runs a major shipyard to build submarines.

The military suspects Pyongyang used a small submarine to test the missile, dismissing speculation that the regime mobilized its latest 3,200-ton ship, which is believed to be under development.

The missile, however, could be a new mini-SLBM shown at the North’s defense exhibition a week earlier, the military said, noting it flew about 590 kilometers at an altitude of 60 kilometers, demonstrating a much shorter flight range than that of the Pukguksong-5 series, Pyongyang’s latest SLBM lineup.

North Korea last tested an SLBM in October 2019, but has never openly carried out a full SLBM test using a submarine large enough to fire multiple missiles.

Experts said the launch, which marks the eighth weapons test this year, was a follow-up on the regime’s plan to improve its weapons. The launch had less to do with projecting strength in the face of a three-way gathering of nuclear envoys from South Korea, the US and Japan this week, they added.

“This kind of test takes months, not days, to prepare in advance. This is Kim following through on his promise at the January party congress that he would reveal better weapons,” said Shin Jong-woo, a senior analyst at the Korea Defense and Security Forum, referring to the North’s leader Kim Jong-un.

It is clear that Kim intends to pursue weapons tests until his demands are met for any resumption of talks, Shin added.

Kim, who said Seoul and Washington were not the “enemy,” insists that the two allies meet his conditions for dialogue. They mainly involve granting Pyongyang sanctions relief and allowing the regime to run its weapons tests, which it says are part of self-defense and not a provocation.

Cheong Seong-chang, director of the Center for North Korean Studies at the Sejong Institute, said North Korea will see to more weapons tests until February next year, when speculation over peace talks runs high as China opens the Winter Olympics. 

“That’s when Kim Jong-un would most likely return to offering half-hearted peace overtures to the outside world on the sidelines of the Olympics. Kim knows how to work the event to his advantage,” Cheong said, referring to the 2018 PyeongChang Games.

The two Koreas started a string of talks in April 2018, two months after the Olympics. But they failed to translate the momentum for diplomacy into concrete action as they found themselves at odds over which step to take between denuclearization and sanctions relief.

Cheong added the Moon Jae-in administration, which is looking to sign an end-of-war declaration to succeed the 1950-53 Korean War armistice as part of revitalizing peace efforts, would not be able to bring North Korea back to table, because the regime is not interested in the proposal.

North Korea has said South Korea should honor peace deals first before signing the declaration, referring to agreements the two Koreas reached at the 2018 summits that the two neighbors would stop all hostilities.

Choi Kang, acting president of the Asan Institute for Policy Studies in Seoul, said the Moon government should stop doubling down on efforts to offer a deal North Korea would find least attractive.

Cheong Wa Dae, which convened a National Security Council meeting, expressed deep regret over North Korea’s missile test, urging the regime to return to dialogue. The Unification Ministry, which handles inter-Korean affairs, said it will carry on with work to defuse tension.