North Korea has failed to launch a missile on its east coast, South Korean and US military officials say, a day after Pyongyang warned the US amid rising tension in the region.
The US said a ballistic missile exploded within seconds of the launch.
Hours earlier, North Korea paraded what appeared to be long-range ballistic missiles at a major military display.
It has already conducted five nuclear tests and a series of missile launches in contravention of UN resolutions.
The latest development comes as US Vice-President Mike Pence heads to the South Korean capital, Seoul, where he is expected to discuss the best way to deal with North Korea’s missile and nuclear programmes.
“North Korea attempted to test an unidentified type of missile from [its eastern port of] Sinpo,” the South Korean defence ministry said, adding that the launch on Sunday had “failed”.
The ministry said that it was investigating for further details.
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The US Pacific Command later confirmed the failed test, adding that it had detected and tracked what it believed to be a North Korean ballistic missile.
“The missile blew up almost immediately,” said US Navy Commander Dave Benham, quoted by Reuters.
One unnamed US official said it was unlikely to have been an intercontinental missile, but investigations were continuing.
Analysis: Stephen Evans, BBC News, Seoul
North Korea frequently tests missiles, in contravention of UN resolutions. The success rate has been improving but its record is still hit and miss. This failure underlines that Saturday’s huge parade in Pyongyang of rows and rows of missiles of different types does not mean the country yet has an effective nuclear arsenal.
Recently, the US has reacted minimally to news of North Korean military exploits. This might be taken as “the time for words is over, now is the time for action”. But what action?
The US is aware of the potential cost of attacking North Korea, given that Seoul is within easy range of North Korean artillery. And China would be unlikely to stand aside if an attempt were made to topple Kim Jong-un (though the US has said that regime change is not an aim).
So what action might President Trump take? Only he knows the answer to that – or perhaps he does not.
‘Threat to whole world’
On Saturday, North Korea marked the 105th anniversary of the birth of its founding president, Kim Il-sung, with a huge military parade in Pyongyang amid speculation that current leader Kim Jong-un could order a new nuclear test.
The event, which appeared to include new intercontinental and submarine-launched ballistic missiles, was a deliberate show of strength.
“North Korea showing a variety of offensive missiles at yesterday’s military parade and daring to fire a ballistic missile today is a show of force that threatens the whole world,” South Korea’s Foreign Ministry said in a statement.
Tension continues to rise in the Korean Peninsula with a US aircraft carrier group steaming towards the region.
Mike Pence’s long-planned 10-day trip marks his first official visit to the region, where he is expected to reaffirm the US commitment to stand by its regional allies.
It comes as Washington steps up the pressure on the isolated North, with President Donald Trump saying that the US is ready to act alone to deal with the nuclear threat.
At the parade on Saturday, North Korean military official Choe Ryong-hae, who is believed to be the country’s second most powerful official, said that his country was “prepared to respond to an all-out war with an all-out war”.
“We are ready to hit back with nuclear attacks of our own style against any nuclear attacks,” he said.
Earlier this month, North Korea test-fired a medium-range ballistic missile from Sinpo into the Sea of Japan.
The launch took place on the eve of a visit by China’s President Xi Jinping to the US to meet Mr Trump. The two later discussed how to rein in North Korea’s nuclear and missile programmes.
On Friday, China’s Foreign Minister Wang Yi warned that the situation in the region was escalating, adding that “conflict could break out at any moment”. Mr Wang said that if war occurred, there could be no winner.
North Korea’s aim is to be able to put a nuclear warhead on an intercontinental ballistic missile (ICBM) that can reach targets around the world.
Pyongyang has claimed to have miniaturised nuclear warheads for use on missiles, though experts have cast doubt on that given the lack of evidence.
The state is banned from any missile or nuclear tests by the UN, though it has repeatedly broken those sanctions.