It was the first clarity from the Trump administration since the president took to social media last week to say he had “instructed the Department of War to start testing our Nuclear Weapons on an equal basis.”

“I think the tests we’re talking about right now are system tests,” Wright said in an interview on Fox News’ “Sunday Briefing.” “These are not nuclear explosions. These are what we call noncritical explosions.”

Wright, whose agency is responsible for testing, added that the planned testing involves “all the other parts of a nuclear weapon to make sure they deliver the appropriate geometry and they set up the nuclear explosion.”

The confusion over Trump’s intention started minutes before he held a critical meeting in South Korea with Chinese President Xi Jinping. Trump took to his Truth Social platform and appeared to suggest he was preparing to discard a decades-old U.S. prohibition on testing the nation’s nuclear weapons.

Later that day, as he made his way back to Washington, Trump was coy on whether he really meant to say he was ordering the resumption of explosive testing of nuclear weapons — something only North Korea has undertaken this century — or calling for the testing of U.S. systems that could deliver a nuclear weapon, which is far more routine.

He remained opaque on Friday when asked by reporters about whether he intended to resume underground nuclear detonation tests.

“You’ll find out very soon,” Trump told reporters aboard Air Force One on Friday, as he headed to Florida for a weekend stay.

The U.S. military regularly tests its missiles that are capable of delivering a nuclear warhead, but it has not detonated the weapons since 1992. The Comprehensive Nuclear Test Ban Treaty, which the U.S. signed but did not ratify, has been observed since its adoption by all countries possessing nuclear weapons, North Korea being the only exception.

Trump announced his plans for nuclear tests after Russia announced it had tested a new atomic-powered and nuclear-capable underwater drone and a new nuclear-powered cruise missile.

Russia responded to Trump’s nuclear testing comments by underscoring that it did not test its nuclear weapons and has abided by a global ban on nuclear testing.

The Kremlin warned though, that if the U.S. resumes testing its weapons, Russia will as well — an intensification that would restart Cold War-era tensions.