North Korea has fired two ballistic missiles towards the sea in defiance of UN resolutions.

It is the second weapons test in several days and experts say Pyongyang is pressing ahead with its arms build-up plans while nuclear diplomacy with the US remains stalled.

Meanwhile, South Korea says it had carried out its first underwater-launched missile test.

President Moon Jae-in’s office said he observed the test of a domestically built submarine-launched ballistic missile on Wednesday afternoon, which flew a set distance before hitting a designated target.

The missiles launched by North Korea landed in water between the Korean peninsula and Japan, according to officials in Seoul and Tokyo. South Korea’s military said South Korean and US intelligence authorities are analysing more details about the launches.

Koreas Tensions
People in Seoul watch a TV report about North Korea’s long-range cruise missiles tests on Monday (Lee Jin-man/AP)

“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 coastguard said no ships or aircraft reported damage from the missiles.

The launches were a violation of UN Security Council resolutions that bar North Korea from engaging in any ballistic missile activities, but the council typically does not issue fresh sanctions on Pyongyang when it launches short-range missiles, like the ones fired on Wednesday.

The latest launches came two days after North Korea said it had tested a newly developed cruise missile twice over the weekend. 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 flew about 930 miles, putting all of Japan and US military installations there within reach.

North Korea Military Parade
Pyongyang also showed off its military power in a parade last week (Korean Central News Agency/Korea News Service/AP)

Many experts say the recent tests suggest North Korea is pushing to bolster its weapons arsenal while applying pressure on President Joe Biden’s administration amid a deadlock in nuclear diplomacy between Pyongyang and Washington.

Wednesday’s launches came as Chinese foreign minister Wang Yi was in Seoul for meetings with Mr Moon and other senior officials to discuss the stalled nuclear negotiations with the North.

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.

Mr Moon’s office said the president told Mr Wang that he appreciates China’s role in the international diplomatic push to resolve the North Korean nuclear standoff and asked for Beijing’s continuing support.

Mr Wang said Beijing will continue to support the denuclearisation of the Korean peninsula and improved ties between the Koreas.