N. Korea Fires 'Military Spy Satellite', Seoul Says

North Korea has fired what it claims is a military spy satellite, the South's armed forces said Tuesday, hours after Japan confirmed that Pyongyang had warned it of an imminent launch.

North Korea's previous efforts to put a spy satellite into orbit in May and August both failed, and Seoul, Tokyo and Washington had repeatedly warned Pyongyang not to proceed with another launch, which would violate successive rounds of UN resolutions.

Seoul's military "detected at 10:43 pm (1343 GMT) one alleged military surveillance satellite launched from the Tongchang-ri area in North Pyongan province," South Korea's Joint Chiefs of Staff said.

The rocket and its purported satellite payload "flew to the west of Baengnyeong island", it said, referring to an island near the maritime border between the two Koreas in the Yellow Sea.

The JCS did not give any details on whether the launch appeared to have succeeded or failed.

Japan also confirmed the launch, with Prime Minister Fumio Kishida's office posting on X: "North Korea has launched a suspected ballistic missile".

Space launch rockets and ballistic missiles have significant technological overlap, experts say, but different payloads, and Pyongyang is barred by UN resolutions from any tests involving ballistic technology.

Tokyo warned residents in the southern region of Okinawa to take shelter, but soon lifted the alert, saying the projectile had "passed into the Pacific".

Kishida said he condemned North Korea's missile launch in the "strongest possible terms".

Seoul has been saying for weeks that Pyongyang was in the final stages of preparation for another spy satellite launch, warning it would take "necessary measures" if it went ahead.

The office of South Korean President Yoon Suk Yeol -- who is in London for a state visit -- hinted earlier Tuesday that it would consider suspending the September 19 military agreement, a key deal aimed at de-escalating tensions on the peninsula, in response.

The launch came earlier than expected, as North Korea had on Tuesday informed Japan that it would launch a satellite between Wednesday and December 1.

"The launch that came hours before its time window notification seems to underscore two things: Pyongyang's confidence in success and intention to maximise surprise factor to the outside world," Choi Gi-il, professor of military studies at Sangji University, told AFP.

The North's May launch failed due to the "abnormal" startup of its second-stage engine, and the August launch due to an error in the "emergency blasting system" during the third-stage flight, according to Pyongyang state media at the time.

Seoul's spy agency this month warned Pyongyang's next launch effort was likely to be more successful than its first two efforts, as the North appeared to have received technical advice from Russia, in return for sending at least 10 shipments of weapons for Moscow's war in Ukraine.

Russian President Vladimir Putin suggested in September after meeting with North Korean leader Kim Jong Un that his nation could help Pyongyang build satellites.

Seoul and Washington have both subsequently claimed Pyongyang has been shipping weapons to Russia, with US Secretary of State Antony Blinken warning this month that military ties between North Korea and Russia were "growing and dangerous".

Successfully putting a spy satellite into orbit would improve North Korea's intelligence-gathering capabilities, particularly over South Korea, and provide crucial data in any military conflict, experts say.

In a commentary carried by the North's official Korean Central News Agency Tuesday, Ri Song Jin, a researcher of the National Aerospace Technology Administration, slammed South Korea's own spy satellite plans, saying they were "extremely dangerous military provocations".

Seoul plans to launch its first spy satellite via a SpaceX rocket later this month, South Korean officials have said.

This shows that the North needs "practical and effective capabilities of space-based reconnaissance and surveillance" as a key way of "exercising the war deterrent more clearly and promoting the strategic security balance in the region", KCNA said.

North Korea has conducted a record number of weapons tests this year.

Seoul, Washington and Tokyo have ramped up their defence cooperation in response, and on Tuesday a US nuclear-powered aircraft carrier, the USS Carl Vinson, arrived at South Korea's Busan Naval Base.