Countries want to revive talks on denuclearisation, which have been stalled for two years.
Seoul and Pyongyang have both test-launched ballistic missiles, hours apart from each other, in a display of military assets that comes amid a faltering diplomatic push to strip North Korea of its nuclear programme.
South Korea’s presidential office said it conducted its first underwater-launched ballistic missile test on Wednesday afternoon, and that the domestically built missile, fired from a 3,000-tonne-class submarine, flew a set distance before hitting a designated target.
The statement said the weapon is expected to help South Korea deter potential external threats, boost its self-defence posture and promote peace on the Korean Peninsula.
It would make South Korea only the seventh country in the world with the advanced technology and raises the prospect of a regional arms race.
President Moon Jae-in cited the nuclear-armed North’s “asymmetric capabilities” as a reason for South Korea to develop better missiles.
“Enhancing our missile capability is exactly what’s needed as deterrence against North Korea’s provocation,” the leader said.
Later on Wednesday, North Korean leader Kim Jong Un’s influential sister accused Moon of “slander”, state news agency KCNA reported. Kim Yo Jong said the remarks by the South Korean president were inappropriate and could lead to a breakdown in ties.
Without mentioning the latest launches by the North, Kim Yo Jong said North Korea’s activities were routine defensive measures and complained of an “illogical … foolish attitude” that portrayed South Korean behaviour as a legitimate action to support peace and North Korea’s actions as a threat to peace.
The test followed two short-range North Korean ballistic missile launches detected by South Korea’s military earlier on Wednesday. On Monday, North Korea said it fired a newly developed cruise missile in its first weapons test in six months.
Experts say the North Korean launches show it is pressing ahead with its arms build-up plans while trying to apply pressure on the United States to resume stalled nuclear talks.
It also appears, according to observers, that Moon’s government, which has been actively pursuing reconciliation with North Korea, may be responding to criticism that it is too soft on North Korea.
South Korea’s military said the North Korean missiles, launched from central North Korea on Wednesday, flew about 800km (497 miles) on an apogee of 60km (37 miles) before landing in the waters between the Korean Peninsula and Japan.
“It’s extraordinary timing that you have not one but two Koreas testing ballistic missiles on the same day,” Yonsei University professor John Delury told AFP news agency.
“It does speak to the fact that there’s an arms race in this region that everyone needs to pay attention to.”
The US Indo-Pacific Command said in a statement that the North Korean launches, while highlighting the destabilising impact of Pyongyang’s illicit weapons programme, did not “pose an immediate threat to US personnel or territory, or to our allies”.
The North Korean launches were condemned by Japan as a threat to peace and security in the region.
“The firings threaten the peace and safety of Japan and the region and are absolutely outrageous,” Japanese Prime Minister Yoshihide Suga said. “The government of Japan is determined to further step up our vigilance and surveillance to be prepared for any contingencies.”
Japan’s coast guard said no ships or aircraft reported damage from the missiles.
Wednesday’s launches were a violation of UN Security Council resolutions that bar North Korea from engaging in any ballistic missile activities. But the UNSC is not likely to slap fresh sanctions on North Korea when it launches short-range missiles, like the ones fired on Wednesday.
On Monday, North Korea said it tested a newly developed cruise missile twice over the weekend. Its state media described the missile as a “strategic weapon of great significance”, implying it was developed with the intent to carry nuclear warheads.
According to North Korean accounts, the missile demonstrated an ability to hit targets 1,500km (930 miles) away, a distance putting all of Japan and US military installations there within reach.
The missile tests came as Chinese Foreign Minister Wang Yi was in Seoul for meetings with Moon and other senior officials to discuss the stalled nuclear negotiations with North Korea.
It is unusual for North Korea to make provocative launches when China, its last major ally and biggest aid provider, is engaged in a major diplomatic event.
Moon’s office said the South Korean president had told Wang he appreciates China’s role in the international diplomatic push to resolve the North Korean nuclear standoff and asked for Beijing’s continuing support. Wang said Beijing would continue to support the denuclearisation of the Korean Peninsula and improved ties between the Koreas.
Yang Moo-jin, a professor at the University of North Korean Studies in Seoul, said Wednesday’s launches “looks like North Korea’s indirect message and even request to Beijing for the Korean Peninsula to be addressed as a central agenda issue for China”.
“At the same time, Pyongyang seems to be claiming and stressing that North Korea is taking the lead in the Korean Peninsula issue,” he told AFP news agency.
The nuclear envoys of South Korea, Japan, and the US were meeting in Tokyo this week as well.
Talks between the US and North Korea have stalled since 2019, when the Americans rejected North Korea’s demand for major sanctions relief in exchange for dismantling an ageing nuclear facility.
The government of North Korean leader Kim Jong Un has so far threatened to build high-tech weapons targeting the US and rejected the Biden administration’s overtures for dialogue, demanding that Washington abandon its “hostile” policies first.
It ended a yearlong pause in ballistic tests in March by firing two short-range ballistic missiles into the sea, continuing a tradition of testing new US administrations with weapons demonstrations aimed at measuring Washington’s response and wresting concessions from the White House.
The Biden administration announced it had completed a review of North Korea policy in May and that while denuclearisation remained a priority it would not seek any “grand bargain” with Kim.
US envoy for North Korea, Sung Kim, said on Tuesday the US had no hostile intent towards Pyongyang and hopes it responds positively to offers for talks on its weapons programmes.