Pyongyangâs latest move comes days after Russia used its veto to disband a UN panel monitoring sanctions compliance.
North Korea has fired a suspected intermediate-range ballistic missile into the sea off its east coast.
South Koreaâs Joint Chiefs of Staff said that it detected the launch from the area of the North Korean capital Pyongyang on Tuesday at 6.53am (21:53 GMT on Monday).
âWe have stepped up monitoring and are closely sharing relevant information with the US and Japan,â they added.
Tokyo confirmed the launch, with the coastguard urging vessels to be vigilant and report any fallen objects without approaching them.
Japanese Prime Minister Fumio Kishida condemned the launch, telling reporters North Korea had ârepeatedly launched ballistic missilesâ this year, adding that it was a threat to regional security and âabsolutely unacceptableâ.
The launch was the third of a ballistic missile in 2024, with North Korea saying it is testing a new intermediate-range hypersonic missile powered by a solid-fuel engine.
It comes just days after a Russian veto ended United Nations expert monitoring of North Korean sanctions violations, amid a probe into alleged arms deals between Moscow and Pyongyang, and a week before South Korea holds general elections.
âThe Kim regime prioritizes advancing its military capabilities and doesnât care to stay quiet during the South Korean legislative election campaign,â Leif-Eric Easley, a professor at Ewha University in Seoul, wrote in emailed comments.
âBut firing an intermediate-range missile lacks the shock value of a full-range ICBM [intercontinental ballistic missile] launch or a nuclear test, so itâs unlikely to swing any National Assembly seats. Although Pyongyangâs weapons development remains a major concern, Seoul is currently focused on health care reform, economic policies, and domestic political scandals.â
Pyongyang has continued to develop its military arsenal despite strict international sanctions imposed over its nuclear weapons programme.
It has also declared South Korea its âprincipal enemyâ, shut down agencies dedicated to reunification and outreach, and threatened war over âeven 0.001 mmâ of territorial infringement.
Last month, the United States and South Korea staged one of their major annual joint military exercises, prompting angry retorts and live-fire drills from Pyongyang, which condemns all such exercises as rehearsals for invasion.
Seoul is one of Washingtonâs key regional allies and the US has about 27,000 soldiers stationed in South Korea.