The test is being seen as a major escalation by the North and has been condemned by its neighbours and the US.
A banned intercontinental ballistic missile (ICBM) has been tested by North Korea.
South Korea and Japan said the ICBM was tested for the first time since 2017, according to a report by
BBC.
Japanese officials said it flew 1,100 km (684 miles) and fell in Japanese waters after flying for over an hour.
ICBMs, designed for nuclear arms delivery, could extend North Korea's strike range as far as the US mainland.
The test is being seen as a major escalation by the North and has been condemned by its neighbours and the US.
North Korea has launched a flurry of missile tests in recent weeks.
The US and South Korea have said some of those tests, which Pyongyang claimed were satellite launches, were in fact trials of parts of an ICBM system.
Thursday's missile appeared to be newer and more powerful than the one North Korea fired five years ago, reaching an altitude of more than 6,000km (3,730 miles), according to Japanese officials.
South Korea's military responded with five missile tests of its own, from land, sea and air. The United States condemned the North for a "brazen violation" of UN Security Council resolutions.
"The door has not closed on diplomacy, but Pyongyang must immediately cease its destabilising actions," White House spokeswoman Jen Psaki said.
Outgoing South Korean President Moon Jae-in condemned what he said was a "breach of the suspension of intercontinental ballistic missile launches promised by Chairman Kim Jong-un to the international community".