North Korea fired three short-range projectiles off its east coast on Monday, South Korea's military said, two days after the North threatened to take "momentous" action to protest outside condemnation over its earlier live-fire exercises.

Key points: In the past 10 days, North Korea has said leader Kim Jong-un supervised two rounds of live-fire artillery exercises in its first weapons tests since late November

In the past 10 days, North Korea has said leader Kim Jong-un supervised two rounds of live-fire artillery exercises in its first weapons tests since late November North Korea insists it has the right to conduct military drills in the face of US and South Korean forces on its doorstep

North Korea insists it has the right to conduct military drills in the face of US and South Korean forces on its doorstep Nuclear talks between North Korea and the US remain stalled since the breakdown of a second summit between Mr Kim and President Donald Trump in 2019

Seoul's Joint Chiefs of Staff said the multiple kinds of projectiles fired from the eastern coastal town of Sondok flew as far as 200 kilometres at a maximum altitude of 50 kilometres before landing in the waters between the Korean Peninsula and Japan.

A JCS statement said South Korea expressed "strong regret" over the launches that, it said, violate a past inter-Korean agreement aimed at lowering military animosities.

South Korea's national security director, Defence Minister and spy chief held an emergency video conference and agreed the North Korean action was not helpful to efforts to establish peace on the Korean Peninsula, according to South Korea's presidential Blue House.

Japan's Chief Cabinet Secretary Yoshihide Suga said North Korea fired suspected ballistic missiles.

He said the multiple North Korean projectiles travelled 100 to 200 kilometres but none landed inside Japan's exclusive economic zone.

"North Korea's latest action, on top of its repeated firings of ballistic missiles, is a serious threat to the peace and safety of Japan and … a grave problem for the entire international society," Mr Suga said.

In the past 10 days, North Korea has said leader Kim Jong-un supervised two rounds of live-fire artillery exercises in its first weapons tests since late November.

Mr Kim had entered the new year with a vow to bolster his nuclear deterrent and not to be bound by a major weapons test moratorium amid a deadlock in US-led diplomacy aimed at convincing Mr Kim to abandon his nuclear program in return for economic and political benefits.

South Korea and some European countries protested against the second North Korea drills on March 2, which they believe involved ballistic missile launches in a violation of UN Security Council resolutions.

North Korea insists it has the right to conduct military drills in the face of US and South Korean forces on its doorstep.

The US has said sanctions on North Korea will stay in place unless it takes significant steps toward denuclearisation. ( AP: Ahn Young-joon )

The UN Security Council did not issue any statement after discussing North Korea's March 2 drills, but five European members condemned what they called "provocative actions".

Belgium, Estonia, France, Germany and the United Kingdom said afterwards that the tests undermine regional and international peace, security and stability.

The North's Foreign Ministry on Saturday accused the five European countries of "repeating an absurd argument of condemnation and violation resolutions of the UN whenever we conducted military drills."

"The reckless behaviour of these countries, instigated by the US, will become a fuse that will trigger our yet another momentous reaction," a ministry statement said.

Last week, Kim Jong-un's younger sister levelled diatribes and crude insults against South Korea for criticising its earlier live-fire exercises, but her statement was followed by Mr Kim sending a letter to South Korean President Moon Jae-in expressing condolences over its coronavirus outbreak.

Some experts say North Korea may intend to catch South Korea off-balance before seeking help in reviving its dilapidated economy, since the US has said sanctions on North Korea will stay in place unless it takes significant steps toward denuclearisation.

"The coronavirus is likely exceeding North Korea's public health capacity, so Kim Jong-un is playing a two-level game," said Leif-Eric Easley, associate professor at Seoul's Ewha Womans University

"At the domestic level, his regime claims to protect the people with drastic quarantine measures and military exercises against external threats.

"Pyongyang may be seeking international assistance, but remains obsessed with not appearing in an inferior position to Seoul."

Nuclear talks between Pyongyang and Washington remain stalled since the breakdown of a second summit between Mr Kim and President Donald Trump in Vietnam in early 2019.

Subsequent talks between the two countries failed to produce much progress amid disputes over how much sanctions relief should be given in return for a limited step to move away from nuclear weapons by North Korea.

AP