Ernest Moniz, who was appointed to the role by President Barack Obama, said during an MSNBC interview on Sunday that even before Russia’s invasion of Ukraine, the risk of countries using nuclear weapons was high. But after President Vladimir Putin raised the alert level of his nuclear forces, “that level of risk is even much, much higher.”

“We have said before that we think that the risk of nuclear use is higher today than it has been since the Cuban Missile Crisis, and that was a statement made before the Ukraine escalation and Putin’s alerting of his nuclear forces,” Moniz noted.

Russia invaded Ukraine last week, causing the U.S. and Europe to retaliate with economic sanctions targeting Russia’s banks and wealthy oligarchs, among other measures. In response to what Putin called “aggressive comments” about Ukraine from Western countries, he put his nuclear forces into “special combat readiness,” a heightened alert level. 

Up until last week, the U.S. and Russia were meeting regularly to discuss the revival of the Intermediate-Range Nuclear Forces Treaty, a nuclear arms control treaty that former President Donald Trump abandoned in 2019.

Putin’s decision to put his nuclear forces on alert has already done damage by making it seem as though nuclear weapons should be at the heart of a country’s security strategy, instead of a deterrent that should not be used, Moniz told MSNBC.

“It has elevated again the role of nuclear weapons in the mind of leaders’ security strategy, so frankly, we’ve already taken a couple of steps back,” he said.

There has been speculation, Moniz noted, that Russia could use smaller missiles called “tactical nuclear weapons” to escalate on the path to de-escalation. This would be a fatal mistake, because using nuclear weapons is more likely to escalate a conflict, Moniz said.

“It’s very very important that we stand down, certainly from this nuclear precipice that we are way too close to today, given Putin’s statement,” he said.