North Korea has confirmed it launched a new intercontinental ballistic missile (ICBM) towards waters off its eastern coast in what was the longest flight time yet for a North Korean missile, authorities in South Korea and Japan said, raising fears of advanced weapons development by Pyongyang.

North Korean leader Kim Jong Un was present at the missile test launch and issued a warning to his enemies, the KCNA state news agency said.

“The test-fire is an appropriate military action that fully meets the purpose of informing the rivals, who have intentionally escalated the regional situation and posed a threat to the security of our Republic recently, of our counteraction will,” Kim was quoted as saying by KCNA.

South Korea’s Joint Chiefs of Staff (JCS) said in a statement the missile launched towards the East Sea, which is also known as the Sea of Japan, was detected at about 7:10am local time (22:10 GMT) and was fired on a “lofted trajectory”.

The JCS said later that initial analysis points to a possible use by North Korea of a newly developed solid-fuel booster for its long-range missiles.

Japan’s Defence Minister Gen Nakatani said the missile, which splashed down about 300km (190 miles) west of Japan’s Okushiri Island, off the country’s northern Hokkaido region, had flown the longest time of any of Pyongyang’s past missile tests.

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

“I think it may be different from conventional missiles,” he said.

North Korea’s launch of longer-range missiles in “lofted trajectory” means firing the missile almost vertically. This allows a missile to travel to a very high altitude but then land a short horizontal distance from the launch site. Such launches are said to enable Pyongyang to gather data to better understand the challenges faced when a long-range warhead re-enters the Earth’s atmosphere.

According to South Korea and Japan, the missile on Thursday recorded a flight time of 87 minutes, longer than the last ICBM test launch in December 2023, which clocked in at 73 minutes. The trajectory of the missile reached an altitude of 7,000km (4,349 miles) and flew a distance of 1,000km (621 miles), the Japanese government said, calling it an ICBM-class missile.

The latest missile launch comes a day after South Korea’s military intelligence agency told lawmakers that North Korea has likely completed preparations for its seventh nuclear test and was close to test-firing a long-range missile capable of reaching the United States.

US National Security Council spokesperson Sean Savett called the launch a “violation” of multiple United Nations Security Council resolutions that he said “needlessly raises tensions and risks destabilising the security situation in the region”.

The launch also comes amid concerns about North Korea’s reported troop dispatch to Russia to support its war against Ukraine.

Speaking at a news conference in Washington with South Korean Defence Minister Kim Yong-hyun on Wednesday, US Defense Secretary Lloyd Austin said North Korean troops wearing Russian uniforms and carrying Russian equipment are moving towards Ukraine, in what he called a dangerous and destabilising development.

South Korea reports that North Korea has sent more than 11,000 troops to Russia and that more than 3,000 of them have been moved close to fighting in western Russia.

Shin Seung-ki, head of research on North Korea’s military at the state-run Korea Institute for Defense Analyses, said the missile launch was likely to test the improved booster performance of an existing ICBM – possibly with the help of Russia.

“North Korea will want to keep getting help like this because it saves times and costs while improving performance and upgrading the stability of weapons system,” he said.

Having come under pressure over its engagement with Russia in Ukraine, “the intention may be to show that it will not bow to pressure, that it will respond to strength with strength, and also to seek some influence on the US presidential election,” Shin added.