President Trump posted on social media Wednesday that he has instructed the Department of War to start testing nuclear weapons “immediately.” The U.S. has observed a voluntary moratorium on nuclear explosive testing since 1992.

There was no indication that the U.S. would start detonating warheads, and the military already regularly tests its missiles and other equipment.

The president suggested changes were necessary because other countries were testing their weapons. Russia has announced multiple tests recently.

Trump wrote on social media while en route to Busan that the Pentagon will “start testing our Nuclear Weapons on an equal basis” and “that process will begin immediately.”

“The United States has more Nuclear Weapons than any other country. This was accomplished, including a complete update and renovation of existing weapons, during my First Term in office,” he wrote on Truth Social. “Because of the tremendous destructive power, I HATED to do it, but had no choice! Russia is second, and China is a distant third, but will be even within 5 years. Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately.”

The White House did not immediately respond to questions seeking more details.

The Associated Press contributed to this story.