North Korea fired an intercontinental ballistic missile (ICBM) just hours before the leaders of South Korea and Japan were due to meet for landmark talks.
Both Japanese and South Korean officials confirmed the long-range missile's launch on Thursday morning.
It flew about 1,000km (620 miles) landing in waters west of Japan.
It is Pyongyang's fourth missile launch in a week and comes as the US and South Korea hold joint navy drills.
The other missiles launched – last Thursday, on Saturday and on Monday – had been short-range ballistic missiles.
North Korea's ramped-up missile activity will most likely be top of the agenda when South Korean President Yoon Suk Yeol meets Japan's Prime Minister Fumio Kishida in Tokyo later on Thursday – the first such visit in 12 years.
Since Monday, the US and South Korea have been carrying out drills around the Korean peninsula- the allies' largest in five years. North Korea has repeatedly said it sees such exercises as provocation.
Thursday's missile was fired at 07:10 (22:10 GMT) from Pyongyang on the east coast of North Korea, South Korea's Joint Chiefs of Staff said.
Japan's defence ministry confirmed it as an ICBM type and said it flew higher than 6,000km for about 70 minutes. It landed at about 08:20 outside of Japan's exclusive economic zone, the ministry said.
Japan officials have not reported any damage from the missile.
Following Thursday's launch, Mr Yoon ordered his country's military to continue with the joint US exercises as planned.
Pyongyang would pay for its "reckless provocations", he said.
North Korea last fired an ICBM less than a month ago – an action that sparked a UN emergency meeting and condemnation from G7 countries.
ICBMs are particularly worrying because of their long range. Experts have said that such missiles launched from North Korea could potentially reach mainland United States.
Pyongyang is also believed to have developed ICBMs that can carry multiple warheads.
The escalation in North Korean aggression over the past year is one of the central topics to be discussed at the Tokyo meeting on Thursday.
Many hope the meeting – which has been hailed as a "milestone" in the rapprochement of South Korea and Japan – will result in closer security ties and military cooperation between the two countries.
Both countries said they would convene their national security councils following Thursday's missile launch.
In 2022, North Korea launched more than 90 missiles – the most it has ever fired in a single year to date – despite being subject to a raft of sanctions from the UN, the US, the EU and its neighbouring countries.
North Korea has become more assertive in its nuclear strategy under Kim Jong-un, who has overseen much of its recent development of its weapons programme, and four of the six nuclear tests so far.
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