President Donald Trump said he’s restarting U.S. nuclear missile testing on Wednesday hours before meeting with Chinese President Xi Jinping, further escalating the stakes of the high-profile summit between the two leaders.

Trump wrote in a social media post he instructed the Pentagon to “immediately” begin testing nuclear weapons “on an equal basis” with nuclear testing programs in other nations, specifically noting the nuclear stockpiles of Russia and China.

“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,” Trump wrote. “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,” he continued. “That process will begin immediately.”

When asked during his official greeting with Xi about the decision, Trump paused and replied: “Thank you very much everybody.”

The tests would likely be seen by foreign adversaries as a proclamation of U.S. military force. The U.S. has not conducted a nuclear test since 1992.

Trump’s statement comes shortly after Russian President Vladimir Putin announced Wednesday that Russia successfully tested a nuclear torpedo capable of damaging entire coastal regions.

Trump’s statement amplifies the significance of his meeting with Xi in South Korea, already a high-stakes affair as the two nations circle another potential trade dispute that could send shockwaves through the market.