A North Korean propaganda outlet on Thursday denounced South Korea's decision to participate in an upcoming annual US-led multinational air force drill with Japan.

Earlier, the Air Force announced its plans to send F-15K fighter jets, cargo planes and dozens of troops to the Red Flag-Alaska 21-2 exercise set to take place in Alaska beginning next week.

"The reality is that the South Korean military is going through fire and water for the US, obsessed with following its scheme to invade Korea and realize the Indo-Pacific strategy," Meari, a North Korean propaganda website, said.

"As the world's largest combat training exercises, the drills are already well known for its belligerent and invasive nature," it added.

The website also slammed South Korea for participating in a total of 153 joint exercises last year amid the global coronavirus pandemic.

It then stressed that the recent strengthening of security ties among Seoul, Washington and Tokyo is undoubtedly targeted toward the North.

The upcoming event will be the first major combined military exercise involving the three nations under the Joe Biden administration, which has called for the improvement of security ties between Seoul and Tokyo to better deal with North Korea and China.

South Korea's Air Force last participated in the Red Flag program in 2018.

Launched in 1975, the Red Flag-Alaska drill is designed to integrate various forces and provide them with training opportunities in a realistic threat environment, according to the US military. (Yonhap)