North Korea fired ballistic missiles, Seoul and Tokyo say

North Korea fired two ballistic missiles into the sea in its latest weapons test in the early hours of Thursday, South Korea and Japan said.

Two short-range ballistic missiles were fired from the North Korean town of Hamju and travelled some 450 kilometres at an altitude of 60 kilometres, the South Korean military's Joint Chiefs of Staff (JCS) said.

The JCS said South Korean and US intelligence were analysing the projectiles in detail.

Japanese Prime Minister Yoshihide Suga also said the projectiles were ballistic missiles.

Suga said Tokyo is making "a serious protest" after Pyongyang fired the missiles into the Sea of Japan - known in South Korea as the East Sea - and that Tokyo "strongly condemns" the act.

"The launch threatens the peace and stability of our country and the region and it was a clear violation of United Nations Security Council resolutions," Suga told reporters.

Japan's Ministry of Defence and South Korea's JCS said the first missile was launched at 2206 GMT and the second shortly before 2230 GMT.

It marks the second time Pyongyang has launched missiles in the past week.

North Korea fired two cruise missiles off its west coast on Sunday, Yonhap reported on Wednesday.

According to a senior US administration official, the weekend launches were part of "normal testing" not in violation of UN Security Council resolutions.

That test on Sunday came in the wake of joint military exercises by the armed forces of South Korea and the US. The nine-day command exercise, which did not include field training, ended on Thursday last week.

The influential sister of North Korean ruler Kim Jong Un, Kim Yo Jong, had condemned the military exercises and accused the new US administration of wanting to cause trouble as a first step.

The rogue nuclear nation is banned from testing ballistic missiles by UN resolutions, and has been slapped with tough international sanctions to deter it from continuing to develop rockets that could be equipped with nuclear warheads.

The sanctions imposed as a result of the weapons programme are hampering North Korea's economic development.

Washington's negotiations with Pyongyang over its nuclear weapons programme have not made any progress since former president Donald Trump's failed summit with North Korean leader Kim Jong Un in Vietnam in February 2019.

Although Trump touted his friendly relationship with Kim, the two sides failed to agree on a roadmap for North Korea's disarmament and what Pyongyang could receive in return.

According to media reports, the US has been trying to contact North Korea since mid-February.

During a visit to Seoul on Wednesday, Russian Foreign Minister Sergei Lavrov called for resuming negotiations on a solution to the problems on the Korean Peninsula.

Russia was committed to a "peaceful and stable situation" in the region, Lavrov said.

"This presupposes that the sides renounce the continuation of their arms race and the expansion of military activities in all formats," he said.

Several foreign policy experts in Moscow viewed the latest missile launch as North Korea signalling to the new US administration it was willing to protect its own sovereignty .