When the U.S. President fired his latest social media missive, about an hour before his much-anticipated summit with Chinese counterpart Xi Jinping in South Korea on Thursday, it seemed more aimed at Russia’s President Vladimir Putin.

On Truth Social around 9 p.m. ET Wednesday, Donald Trump warned that the U.S. has “tremendous destructive power” with respect to nuclear weapons. “Because of other countries testing programs,” he announced, “I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately.” Trump’s post came after Russia recently revealed that it had conducted several tests of nuclear “superweapons,” including an underwater drone designed to evade interception and to create a potentially devastating tsunami at its target.