A North Korean flag flutters on top of a 160-metre tower in North Korea's propaganda village of Gijungdong, in this picture taken from the Tae Sung freedom village near the Military Demarcation Line (MDL), inside the demilitarised zone separating the two
A North Korean flag flutters on top of a 160-metre tower in North Korea's propaganda village of Gijungdong, in this picture taken from the Tae Sung freedom village near the Military Demarcation Line (MDL), inside the demilitarised zone separating the two Koreas, in Paju, South Korea, April 24, 2018. Reuters / Kim Hong-Ji

North Korea fired a ballistic missile toward the sea off its east coast on Wednesday, South Korea and Japan said, about a week after Pyongyang vowed to develop its nuclear forces "at the fastest possible speed".

The North's 14th known weapons test this year comes days before the South's new president, Yoon Suk-yeol, takes office on May 10. The North's last test, on April 16, involved a new tactical guided weapon aimed at boosting its nuclear capability.

South Korea's Joint Chiefs of Staff (JCS) said it detected the launch about noon in the Sunan area of the North's capital of Pyongyang, home to an international airport and the area from which the North said it had fired its largest intercontinental ballistic missile (ICBM), the Hwasong-17, on March 24.

The missile flew about 470 km (292 miles) to a maximum altitude of 780 km (485 miles), the JCS said.

"A recent series of North Korea's ballistic missile launches poses a grave threat to the peace and stability of not only the Korean peninsula but also the international community," the JCS said in a statement, urging the North to immediately stop such actions.

The offices of both outgoing and incoming South Korean presidents strongly condemned the launch, with Yoon's team vowing to strictly respond to such actions and devise "more fundamental deterrent measures".

Japan's Coast Guard also reported a suspected ballistic missile launch by North Korea.

Japanese deputy defence minister Makoto Oniki put the missile's range at 500 km (311 miles) and its maximum altitude at 800 km (497 miles). He said the ministry was still analysing the data to determine its type.

"North Korea's recent action, including frequent missile launches, cannot be tolerated, as it poses a threat to security and safety of the region and international community," Prime Minister Fumio Kishida told reporters, adding that Japan had logged a protest against North Korea.

ANOTHER TEST OF SPY SATELLITE?

When he oversaw a huge military parade last week, North Korean leader Kim Jong Un pledged to hasten development of the country's nuclear arsenal amid stalled denuclearisation talks with the United States.

In Seoul, officials and experts say it is too early to say if the latest test involved an ICBM.

In its March 24 test, the North's first full-capability launch since 2017, a missile flew 1,080 km (671 miles) to an altitude of 6,200 km (3,900 miles), with a flight time of 71 minutes, the JCS said.

"It might be an ICBM or something with a shorter range," Lee Jong-sup, Yoon's pick for defence minister, said at his confirmation hearing on Wednesday.

Ankit Panda, a nuclear policy expert at the U.S.-based Carnegie Endowment for International Peace, said the launch possibly involved technology for satellite reconnaissance systems, which the North tested in February and March.

Cheong Seong-chang, a specialist on North Korea at the Sejong Institute think tank in Seoul, agreed.

"Today's range and maximum altitude was similar to those recorded in the two previous tests, but showed progress in its capability," Cheong said.

Wednesday's test came as South Korean and Japanese nuclear envoys held talks in Seoul, urging the North to stop escalating tension and return to diplomacy, Seoul's foreign ministry said.

China's nuclear negotiator, Liu Xiaoming, also met Vice Foreign Minister Choi Jong-kun, who called for Beijing's constructive role in stabilising the situation, the ministry said.

Ahead of Yoon's inauguration, he is mapping out a foreign policy agenda after signalling a tough line against Pyongyang, while leaving open the door for dialogue.

Lee, a retired former deputy chairman of JCS, told the hearing he would beef up South Korea's deterrent capability to "sternly" respond to the North's nuclear and missile threats.

After breaking its 2017 moratorium on long-range missile testing, North Korea may also soon resume nuclear tests, officials in Seoul and Washington say.

Asked at the hearing about a potential new nuclear test, Lee said preparations seemed to be under way, possibly for a smaller, tactical nuclear weapon.