The South Korean, US and Japanese militaries have conducted their first-ever trilateral aerial exercise in response to evolving North Korean nuclear threats, South Korea’s air force said.

The training held near the Korean Peninsula was to implement the three countries’ earlier agreement to increase defence cooperation and boost their joint response capabilities against North Korean threats, the air force said.

The drill involved a nuclear-capable B-52 bomber from the United States and fighter jets from South Korea and Japan, the statement said.

South Korea and Japan are both key US allies in Asia, which together host about 80,000 American troops.

The three countries have occasionally held trilateral maritime drills, such as anti-submarine or missile defence exercises, but Sunday’s training marked the first time they performed a trilateral aerial drill.

In South Korea, expanding military drills with Japan is a sensitive issue, because many still harbour strong resentment against Japan’s brutal 1910-45 colonial rule over the Korean Peninsula.

But the North’s advancing nuclear programme has pushed South Korea’s conservative president, Yoon Suk Yeol, to move beyond historical disputes with Japan and beef up a trilateral security cooperation with the US and Japan.

In August, Mr Yoon, US President Joe Biden and Japanese Prime Minister Fumio Kishida met at Camp David in their countries’ first stand-alone trilateral summit and agreed to bolster their defence cooperation to deal with North Korea’s nuclear threats.

The three leaders decided to hold annual trilateral exercises and put into operation by year’s end the sharing of real-time missile warning data on North Korea.

Sunday’s drill could draw a furious response from North Korea, which has long bristled at US training exercises with South Korea, calling them an invasion rehearsal and responding with missile tests.

The North slammed the Camp David agreement, accusing the US, South Korean and Japanese leaders of plotting nuclear war provocations on the Korean Peninsula. North Korean leader Kim Jong Un called Mr Yoon, Mr Biden and Mr Kishida “the gang bosses” of the three countries.

Worries about North Korea’s nuclear programme have deepened after it enacted a law that authorises the pre-emptive use of nuclear weapons last year, and has since openly threatened to use them in potential conflicts with the US and South Korea.