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.

“In terms of speed and operating depth, there is nothing like this unmanned vehicle anywhere in the world, and it’s unlikely that anything similar will appear in the near future,” Putin said Wednesday.

Last week, Putin hailed the successful testing of an “unlimited-range” nuclear-powered missile that he also described as a “unique weapon that no other country possesses.” Trump rebuked Putin at the time, saying that it was not an “appropriate” topic for Putin, who “ought to get the war ended,” referring to Russia’s ongoing war of invasion against Ukraine, which began in February 2022.

Trump also warned that the U.S. “test[s] missiles all the time” and has “a nuclear submarine, the greatest in the world, right off [Russia’s] shore, so it doesn’t have to go 8,000 miles.”