North Korea said Thursday it’s prepared to counter U.S. military moves with the “most overwhelming nuclear force” as it warned that the expansion of the United States’ military exercises with rival South Korea is pushing tensions to an “extreme red line.”

The statement by Pyongyang’s Foreign Ministry came in response to comments by U.S. Defense Secretary Lloyd Austin, who said Tuesday in Seoul that the United States would increase its deployment of advanced military assets to the Korean Peninsula, including fighter jets and aircraft carriers, as it strengthens joint training and operational planning with South Korea.

South Korea’s security jitters have risen since North Korea test-fired dozens of missiles in 2022, including potentially nuclear-capable ones designed to strike targets in South Korea and the U.S. mainland.

In a statement attributed to an unidentified spokesperson of its Foreign Ministry, North Korea said the expansion of the allies’ drills is threatening to turn the Korean Peninsula into a “huge war arsenal and a more critical war zone.” The statement said the North is prepared to counter any short- or long-term military challenge with the “most overwhelming nuclear force.”