As military setbacks in Ukraine force Russian President Vladimir Putin into a corner, an ex-CIA officer predicts that he will resort to tactical nuclear weapons.

“I think the chances of him de-escalating are close to zero… he simply cannot give up so much ground and be seen to be losing and continue as Russia’s leader,” former CIA case officer Robert Baer told CNN on Tuesday.

“The likelihood of him employing nuclear weapons — at least tactical nuclear weapons — is increasing by the day,” Baer added.

Ukrainian forces have recently liberated thousands of square miles of previously occupied territory in counteroffensives along the war’s eastern and southern fronts, indicating a shift in Putin’s approach to the seven-month-long conflict.

Last week, Russian President Vladimir Putin delivered a rare televised address in which he announced the partial mobilization of his country’s reservists, paving the way for more troops to deploy to Ukraine. Immediately following, Russians took to the streets to protest the war. Fearing a call-up to fight, many fled the country by any means possible.

The Kremlin admitted on Monday that it made mistakes in selecting draftees for deployment to Ukraine and expressed hope that mobilization will speed up once the sanctions are lifted.

However, battlefield setbacks in Ukraine and domestic pressure within Russia will have no effect on Russian President Vladimir Putin, who is unlikely to withdraw troops and negotiate an end to the war, according to Baer.

“He’s a strongman, as he’s portrayed himself for the last 20 years, and he doesn’t back down from dissent. He’s been cornered. He’s completely cornered, and he needs to move forward like a shark “According to Baer, “He is still bombing Ukrainian cities. He keeps grabbing people. He’s still holding his ground, and I don’t see him giving in.”

During his mobilization announcement, Putin also threatened to use nuclear weapons in Ukraine, falsely accusing Western countries of provoking him with “nuclear blackmail,” and claiming that his remarks are not a threat. Russia possesses the world’s largest nuclear arsenal, which is equipped with both strategic nuclear weapons that can be used against cities and tactical nuclear weapons that can be used on the battlefield.

“Russians I communicate with in Russia are convinced he’s going nuclear,” Baer told CNN. “I’m not sure how well-connected they are, but this threat — it was a threat at first — but the more trouble he’s in, the more likely he’ll use nuclear weapons.”

On Monday, State Department Spokesperson Ned Price told reporters that Putin’s “nuclear saber-rattling,” among other things, signals “very clearly that he knows he is losing.”

“He’s on his back heels. And he’s making every attempt to intimidate those who would stand up to him,” Price said. “We – along with our allies and partners around the world – are not going to bow to intimidation.”

The Marshal Shaposhnikov was joined by Steregushchiy-class corvettes RFS Aldar Tsydenzhapov, RFS Sovershennyy, RFS Gromky, and the sea tanker Pechenga, according to Russia’s defense ministry on Friday.

According to Moscow’s statement, China sent the Nanchang, the Type 054A frigate Yancheng, and the Type 903A replenishment ship Dongpinghu of the PLA Navy’s North Sea Fleet. The three warships participated in Russia’s quadrennial Vostok war games earlier this month. A year ago, the Nanchang and the Dongpinghu also took part in Russia-China exercises in the Pacific.