(NewsNation) — Russian President Vladimir Putin has been issuing veiled threats about using nuclear weapons in Ukraine practically since he ordered his military to invade the nation in February. U.S. President Joe Biden says Putin is “not joking.”

On Thursday, Biden said the United State was as close to “nuclear Armageddon” as it has been since the Cuban Missile Crisis of 1962 in what may be the most significant response to Putin’s threats since the war began.

But retired Lt. Gen. Jerry Boykin said he is not convinced Putin is going to turn to his nuclear arsenal anytime soon.

“I don’t think it’s very likely at this point Putin will use a nuclear weapon, even a tactical nuclear weapon, and the reason is he’s gone too far into this war now and the war is over if he does that because I believe the response from NATO will not be a nuclear response,” Boykin said. “It will be an all-out conventional response that will bomb every target in the Ukraine that has any association with his army or his military on the ground in there. They will destroy him.”

Putin’s war in Ukraine has been faltering of late, as the Ukrainian military has made gains against Russian forces in the east, north and south, in a war Russia expected would end quickly and instead has spanned months.

Some fear Putin could turn desperate in a losing war effort and resort to nuclear weapons. Former U.S. ambassador John Bolton said Putin using nuclear weapons would be equivalent to him signing his own “suicide note.”

Boykin, too, feels Putin knows using nuclear weapons is a zero-sum game.

“His arsenal is only as good as a threat, once he fires a nuclear weapon, it’s over,” Boykin said.

The Biden administration meanwhile has issued conflicting statements about how it views Putin’s nuclear threats. Biden delivered his “not joking” and “Armageddon” comments, but others in his circle issued different messaging.

“I don’t see anything right now that would lead me to believe (Putin) has made such a decision (on nukes),” Secretary of Defense Lloyd Austin said.

Boykin said he is not convinced Biden believes what he said.

“It’s hard for anybody to get inside his head and understand exactly what he is trying to say. That’s why he’s got a team there that cleans up behind him … just about every week,” Boykin said. “That said, I don’t know that he necessarily believes Putin is that near using a nuclear weapon. I don’t think that’s the case.”