North Korea fired an intermediate-range ballistic missile (IRBM) over Japan on Tuesday, prompting Tokyo to activate the country's missile alert system and order people to take shelter.
The last time North Korea fired a missile over Japan was in 2017, at the height of a period of "fire and fury" when Pyongyang's leader Kim Jong Un traded insults with then-US president Donald Trump.
South Korea's military said it had detected the launch of an IRBM, which flew around 4,500 km at an altitude of about 970 km and speeds of around Mach 17.
"Specific details are under close analysis by South Korean and US intelligence," the South's Joint Chiefs of Staff added in a statement.
South Korea's President Yoon Suk-yeol called the launch a "provocation" that violated UN regulations
Yoon "ordered a stern response and to take corresponding measures in cooperation with the United States and the international community", his office said in a statement.
Tokyo also confirmed the launch of an IRBM, activating the country's missile alert warning system and urging people to take shelter.
"North Korea appears to have launched a missile. Please evacuate into buildings or underground," the government said in an alert issued at 7:29 am.
National broadcaster NHK said the alert was in effect for two northern regions of the country.
"A ballistic missile is believed to have passed over our country and fallen in the Pacific Ocean. This is an act of violence following recent repeated launches of ballistic missiles. We strongly condemn this," Prime Minister Fumio Kishida told reporters.
Defence Minister Yasukazu Hamada said that North Korea "has in the past launched Hwasong 12-type missiles four times, so this could be the same type".
If so, the flight distance, which Tokyo estimated at 4,600 km, was thought to be a new record for that particular missile.
The last two times North Korea fired Hwasong-12 missiles over Japan, in September and August 2017, they travelled 3,700 km and 2,700 km respectively, Chad O'Carroll of Seoul-based specialist site NK News wrote on Twitter.
"This is the 8th test of the Hwasong-12 and the 3rd time it has overflown Japan," Jeffrey Lewis of the Middlebury Institute of International Studies wrote on Twitter.
With talks long-stalled, nuclear-armed North Korea has doubled down on Kim's military modernisation plans this year, testing a string of banned weaponry, including an intercontinental ballistic missile (ICBM) for the first time since 2017.
Last week, Pyongyang fired short-range ballistic missiles on four occasions, including just hours after US Vice President Kamala Harris flew out of Seoul. (AFP)