The first launch of the year came just hours before South Korea's leader headed to China for a summit that is expected to feature ties with the North.

Seoul's defence ministry said it had detected "several projectiles, presumed to be ballistic missiles" fired from near the North Korean capital Pyongyang around 7:50 am (2250 GMT Saturday).

The missiles flew approximately 900 kilometres (559 miles), the military said, adding that South Korea and ally the United States were "closely analysing the specifications" while "maintaining a full readiness posture".

The launch follows the US operation that snatched Venezuelan President Nicolas Maduro out of his country -- a nightmare scenario for North Korea's leadership, which has long feared a so-called "decapitation strike" of that kind and accused Washington of seeking to remove it from power.

One analyst said Saturday's operation in Venezuela likely played a role in the decision to carry out the launch.

Seoul's Office of National Security convened an emergency meeting following the launch, which a presidency statement said "constitutes a provocative act in violation of United Nations Security Council resolutions".

Japan's defence ministry also said it had detected a possible ballistic missile, noting that two projectiles reached an altitude of 50 kilometres and flew distances of 900 and 950 kilometres respectively.

"North Korea's nuclear and missile development threatens the peace and stability of our country and the international society, and is absolutely intolerable," Japan's Defence Minister Shinjiro Koizumi told reporters.

Pyongyang last launched a ballistic missile in November, when it staged a test after US President Donald Trump approved South Korea's plan to build a nuclear-powered submarine.

In a statement shared by Pyongyang's state media on Sunday, the North Korean foreign ministry condemned the US attack on Venezuela as a "serious encroachment of sovereignty".

"The incident is another example that clearly confirms once again the rogue and brutal nature of the US," it said.

Pyongyang has for decades argued it needs its nuclear and missile programmes as a deterrent against alleged regime change efforts by Washington. The United States has offered Pyongyang repeated assurances that it has no such plans.

"They likely fear that if the United States so chooses, it could launch a precision strike at any moment, threatening the regime's survival," said Hong Min, an analyst at the Seoul-based Korea Institute for National Unification.

"The underlying message is likely that attacking North Korea would not be as easy as a strike on Venezuela," he said.

A former senior North Korean diplomat who defected in 2023 said Pyongyang should learn from the US operation.

It came after Maduro "squandered a valuable opportunity through bluster", Lee Il-kyu, Pyongyang's former political counsellor in Cuba, wrote on social media.

- 'Expansion' -

The test also came as South Korean President Lee Jae Myung was expected in Beijing for talks with his counterpart Xi Jinping, whose government is a key economic backer of North Korea.

Lee hopes to possibly harness China's clout over North Korea to support his bid to improve ties with Pyongyang.

North Korea has stepped up missile testing significantly in recent years.

Analysts say this drive is aimed at improving precision strike capabilities, challenging the United States as well as South Korea, and testing weapons before potentially exporting them to Russia.

Pyongyang is also set to hold a landmark congress of its ruling party in the coming weeks, its first in five years.

Economic policy, as well as defence and military planning, are likely to be high on the agenda.

Ahead of that conclave, leader Kim Jong Un ordered the "expansion" and modernisation of the country's missile production.

State media reported on Sunday that Kim had visited a facility involved in making tactical guided weapons.

He ordered them to expand current production capacity by 250 percent, the state-run Korean Central News Agency said.

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