South Korea, Japan, and the United States have conducted a joint air drill involving a heavy bomber, Seoul’s military said, in response to North Korea’s latest long-range missile test.

The exercise took place on Sunday, three days after Pyongyang launched one of its most powerful and advanced solid-fuelled intercontinental ballistic missiles (ICBM), which experts say could reach targets in the mainland US.

The drill mobilised the US’ B-1B bomber, South Korea’s F-15K and KF-16 fighter jets, and Japan’s F-2 jets, Seoul’s military said.

“The exercise demonstrates the commitment of the ROK-US alliance to integrated extended deterrence in response to the advancing nuclear and missile threats from North Korea,” said South Korea’s Joint Chiefs of Staff in a press release.

During the aerial manoeuvre, South Korea and Japan’s jets escorted the US strategic bomber to a designated location south of the Korean peninsula, “demonstrating an overwhelming capability to swiftly and accurately strike simulated targets,” it added.

The B-1B Lancer is a supersonic heavy bomber known for its high-speed performance with a payload of 34,000 kilograms of munitions, including both conventional and precision-guided weapons.

It was the fourth time this year the bomber was deployed to the Korean peninsula, the military said, and the second time for a trilateral aerial exercise to counter Pyongyang’s military threats.

The North’s latest ICBM launch is said to have flown higher and further than any previous missile, according to North Korea as well as Seoul and Tokyo’s militaries, which tracked it in real-time.

The official Korean Central News Agency hailed it as “the world’s strongest strategic missile,” and leader Kim “expressed great satisfaction” at the successful launch.

North Korea “would never change its line of bolstering up its nuclear forces,” the agency said.

The launch came amid growing international scrutiny over Pyongyang’s purported deployment of thousands of troops to Russia to support Moscow’s war efforts in Ukraine, raising concerns North Korean soldiers in Russian uniforms could soon engage in combat.

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.