Russian President Vladimir Putin is aware he’s "losing this war" against Ukraine and is forcing an annexation referendum vote to score a "political victory" with the Russian people, according to retired four-star Army Gen. Jack Keane.

"He's got to conclude that at least right now he's losing this war. And this is an attempt to obtain a political victory largely for his own domestic audience, that they have gobbled up this increased terrain in four different regions in Ukraine," Keane, Fox News’ senior strategic analyst, told "Fox News Sunday" anchor Shannon Bream of the forced annexation votes taking place. 

Occupying forces in the Ukrainian regions of Luhansk, Dontesk, Zaporizhzhia and Kherson began voting last week on whether Ukrainians in the areas will decide to secede from Ukraine and join Russia. The referendums have been described as a "sham" by Western nations, and Ukrainian officials on the ground described armed Russian forces are coercing residents to vote. 

The voting began Friday at residents’ homes and will continue until Tuesday, when polling stations will open, according to Russian media. 

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Luhansk referendum

A Luhansk People's Republic serviceman votes in a polling station in Luhansk, Luhansk People's Republic, controlled by Russia-backed separatists, eastern Ukraine, Friday, Sept. 23, 2022. Voting began Friday in four Moscow-held regions of Ukraine on referendums to become part of Russia.  (AP Photo)

Keane said that "anybody looking at this knows it's a sham."

"It's not going to mean anything, and it certainly is not going to stop Ukrainians from continuing their military operations inside these territories," he continued.

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People vote on Russia referendum

Residents cast their votes in controversial referendums in the city of Dokuchaievsk, Donetsk Oblast, Ukraine on September 23, 2022.  Voting will run from Friday to Tuesday in Luhansk, Donetsk, Kherson and Zaporizhzhia, with people asked to decide if they want these regions to become part of Russia.  (Photo by Leon Klein/Anadolu Agency via Getty Images)

Putin threatened the use of nuclear weapons last week as the country’s invasion and war against Ukraine continues raging.  

"To those who allow themselves such statements regarding Russia, I want to remind you that our country also has various means of destruction, and for separate components and more modern than those of NATO countries, and when the territorial integrity of our country is threatened, to protect Russia and our people, we will certainly use all the means at our disposal," Putin said in a Wednesday address.

Russian President Vladimir Putin speaks to students wearing suit and tie

Russian President Vladimir Putin delivers an address to the participants of the Bolshaya Peremena All-Russian contest for school students via a video link at the Novo-Ogaryovo state residence, outside Moscow, on June 1, 2022.  (MIKHAIL METZEL/SPUTNIK/AFP via Getty Images)

"It's not a bluff," he added.

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Keane said that such a threat should be taken seriously, but that the "probability of it is pretty low." He argued that Russia’s military isn’t equipped to battle in a radioactive environment and that Ukraine forces are braced for a nuclear attack and remain "steadfast" to fight. 

"Let's assume he's serious and the use of a nuclear weapon is actually on the table, which I think is probably very low. … Here's the factors that [Putin's] got to consider. He would use a nuclear weapon to want to end the war and that's not going to happen. The Ukrainians, the people, as well as their military, are steadfast. They openly talk about the possibility of a nuclear weapon being targeted against them, and they are going to fight and continue to fight," Keane said. "The second thing is his army on the battlefield. They're not trained to deal with a radioactive nuclear battlefield. The Soviet Union was, they were equipped and properly trained. These guys aren't trained to fight a conventional fight much less deal with an environment like that."

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"I believe that Biden administration has reported that they're talking to Putin and his surrogates about the consequences here, and I hope we're very direct with him about what those consequences would mean," he added.

Fox News' Caitlin McFall contributed to this report.