North Korean leader Kim Jong Un described the alliance between the United States, South Korea, and Japan as a “threat to his country,” asserting that he would strengthen Pyongyang’s nuclear program.

In a speech marking the 77th anniversary of the Korean People’s Army, Kim accused Washington of forming a military bloc similar to NATO in the region.

He added that the trilateral security alliance poses a “serious challenge to the security environment of our nation,” according to the Korean Central News Agency.

This comes amid stalled diplomatic efforts between Pyongyang and Washington, while the United States and South Korea have intensified their joint military exercises.