President Donald Trump appeared to suggest Thursday that the U.S. will resume testing nuclear weapons for the first time in three decades, saying it would be on an “equal basis” with Russia and China.

The Kremlin pointed out that a global ban on nuclear tests has remained in place, but warned that if any country resumes nuclear testing Russia would follow suit.

Russian President Vladimir Putin this week announced that Russia tested a new atomic-powered and nuclear-capable underwater drone and a new nuclear-powered cruise missile.

Putin did not announce any tests of Russia’s nuclear weapons, however, which last occurred in 1990.

There was no indication the U.S. would start detonating warheads, but Trump offered few details about what seemed to be a significant shift in U.S. policy.

He made the announcement on social media minutes before he met with Chinese leader Xi Jinping on Thursday in South Korea.

When he spoke to reporters later aboard Air Force One as he flew back to Washington, he offered little clarity.

The U.S. military already regularly tests its missiles that are capable of delivering a nuclear warhead, but it has not detonated the weapons since 1992.