SEOUL: South Korea, the US and Japan held their first joint air drills on Sunday, Seoul’s military said. The exercise, which involved a US nuclear-capable B-52 bomber, comes as Seoul, Washington and Tokyo step up their defense cooperation against rising missile and nuclear threats from North Korea.

A US bomber landed at a South Korean air base on Tuesday after flying over the country’s biggest defense exhibition. Flying at subsonic speeds, B-52s can travel more than 8,800 miles without refueling at altitudes of up to 50,000 feet.

The trilateral exercise took place south of the Korean peninsula, where the air defense identification zones of Seoul and Tokyo overlap, according to the South Korean air force.

“This is the first time that the air forces of South Korea, the United States and Japan have conducted an aerial exercise,” the statement said.

The exercise was planned to expand the response capabilities of the three countries against North Korea’s growing nuclear and missile threats, the statement added.

Pyongyang views any such exercises as rehearsals for an invasion and has repeatedly warned that it will take “massive” action in response.

North Korea rejects Washington’s deployment of long-range military assets and in 2017 threatened to “shoot down” US strategic bombers even outside North Korean airspace.

The B-52’s arrival followed a port visit a week earlier by the nuclear-powered aircraft carrier USS Ronald Reagan, prompting an angry response from Pyongyang.

It also comes ahead of a two-day visit by Russian Foreign Minister Sergei Lavrov to Pyongyang as the neighbors and historic allies under UN sanctions strengthen ties.

Moscow is reportedly interested in buying North Korean munitions, while Pyongyang wants Russia’s help in developing its internationally condemned missile program.

Amid a record series of weapons tests that Pyongyang has broken this year, Seoul has moved to strengthen its security relationship with traditional ally the United States while entering into a trilateral defense pact that also includes Japan.

In August, the leaders of the three countries met at the Camp David summit and agreed on a multi-year plan for regular joint exercises and real-time data sharing on North Korea.

Earlier this month, the three countries conducted a joint naval exercise around the Korean Peninsula for the first time in seven years. The two-day exercise simulated the interception of North Korean smuggling ships, according to the Seoul Navy.