North Korea Fires 'Long-range' Ballistic Missile, Seoul Says

North Korea on Thursday test-fired one of its most powerful missiles, South Korea's military said, Kim Jong Un's first weapons test since being accused of sending soldiers to Russia.

South Korea's military had warned a day earlier that the nuclear-armed North was preparing to test another intercontinental ballistic missile (ICBM) or even conduct a nuclear test, possibly ahead of next week's US elections.

The launch came just hours after US and South Korean defense chiefs called on Pyongyang to withdraw its troops from Russia, warning that North Korean soldiers in Russian uniforms were being deployed for possible action against Ukrainian forces.

"Our military detected one ballistic missile launched from the Pyongyang area toward the East Sea at approximately 7:10 AM (2210 GMT) today," Seoul's Joint Chiefs of Staff said, referring to the body of water also known as the Sea of Japan.

"The ballistic missile is presumed to be a long-range missile launched at a high angle," it said.

North Korea typically test-fires its longest-range and most powerful missiles on a so-called lofted trajectory -- fired up, not out -- which it says is to avoid overflying neighbouring countries.

"Our military has heightened its alert level and is closely sharing information regarding North Korea's ballistic missile with the US and Japan authorities, maintaining a thorough readiness posture," Seoul's JCS added.

Tokyo also confirmed the launch, with Japan's defence minister saying that the missile had flown for longer than any other previously tested by the North.

"It was the longest time flying of any missile so far," Gen Nakatani told reporters.

"I think it may be different from conventional missiles."

South Korea's military told lawmakers Wednesday that "preparations are nearly complete for an ICBM-class long-range missile".

"Preparations for a transporter erector launcher are complete, and it has been deployed to a certain area," the Defense Intelligence Agency told lawmakers, though it said no missile has been mounted yet.

The DIA said the launch could involve an ICBM and be aimed at testing the North's atmospheric reentry technology.

Seoul has also slammed the nuclear-armed North's accelerating deployment of troops to Russia, saying it posed a "significant security threat".

Thousands of North Korean troops had been moved to western Russia, which "suggests they are unlikely to have gone merely for observation," a presidential official said Wednesday.

Seoul, a major weapons exporter, has said it is reviewing whether to send weapons directly to Ukraine in response, something it has previously resisted due to longstanding domestic policy that prevents it from providing weaponry into active conflicts.

Seoul has long accused the nuclear-armed North of sending weapons to help Moscow fight Kyiv and alleged that Pyongyang has moved to deploy soldiers en mass in the wake of Kim Jong Un's signing of a mutual defence deal with Russian President Vladimir Putin in June.

North Korea has denied sending troops, but in the first comment in state media last week, its vice foreign minister said that if such a deployment were to happen, it would be in line with international law.

Pyongyang is banned from tests using ballistic technology by multiple rounds of UN sanctions, but Kim Jong Un has ramped up testing this year, with experts warning he could be testing weaponry before providing it to Russia.