US President Joe Biden admitted this week that American diplomats still do not know how Russian President Vladimir Putin can end his stalled war in Ukraine and save face. Western analysts don’t see good options.

The question of Putin’s “off-ramp” — or decisions that will allow him to end the fighting without admitting defeat — has occupied Western politicians and foreign policymakers since the war began in February.

“Where does he find a way out?” Biden asked during a call in New York on Thursday. “Where is he in a position where he loses not only face but significant power within Russia?”

A French diplomat, who recently spoke on condition of anonymity, stressed that what Putin’s thinking is understood by European allies is no more than his desire to secure what appears to be an increasingly unlikely military victory.

“There is a war he cannot win, but what would satisfy him? We have no answers,” said the diplomat.

Rather than seek a negotiated relegation, Putin has escalated in recent weeks, formally annexing four regions of Ukraine on September 30 and authorizing a partial mobilization of up to 300,000 men for the war.

“He may think that the situation on the battlefield is not great, but things will calm down in the winter, that the Ukrainian attacks will end, that they will be able to mobilize,” said Eliot A. Cohen , a military historian and former US State Department adviser, told AFP.

“I think he’s wrong. I think the Russians are in a serious hurting world,” added Cohen, an expert at the Center for Strategic and International Studies at US Johns Hopkins University.

Ukrainians continue to retake occupied areas in the north-east and south, while Kremlin mobilization has sparked rare disagreements in Russia, as evidence shows many recruits lack adequate weapons and equipment.

“Russia’s behavior is irrational,” wrote Joris van Bladel, a think-tank contributor to the Belgian Royal Institute for International Relations. “The only ‘rational’ element the Kremlin relies on is time.”

“Russia is trying to buy time hoping that European countries will collapse before Russia’s demise,” he added.

Putin’s escalation on the ground has also been accompanied by new rhetoric about the possible use of nuclear weapons aimed at Western countries.

Some analysts see this as a bluff, while others see it as a sign of desperation.

“His hope is that references to nuclear weapons will discourage democracies from supplying arms to Ukraine and buy him enough time to bring Russian reserves onto the battlefield to slow the Ukrainian offensive,” wrote Timothy Snyder, an American Historians for Russia and Ukraine this week.

But Biden said Thursday he believed Putin was “not joking” with his threats, adding it was hard to imagine it “didn’t end in Armageddon.”

Western nations have signaled they would feel compelled to respond in some way if Russia crossed the nuclear threshold, raising the risk of direct conflict between the NATO military alliance and Moscow.

“This is a very, very dangerous moment,” former US Secretary of State John Kerry said late last month.

Putin is “more in a corner than anyone would like because that’s not good for anyone,” Kerry told MSNBC Sept. 28.

Cohen said Putin could instead authorize the use of chemical or biological weapons — less provocative than a low-yield nuclear weapon — “but the military utility of those weapons might not be as great.”

As the Russian president continues to up the ante, another “off-ramp” is one that sees Putin bundled out of power either through a popular uprising or — more likely — a “palace coup” in which he is replaced with a rival .

Further mobilization problems, a significant military collapse, or a successful new Ukrainian offensive on a separate part of the front line could increase domestic pressure on Putin, who celebrated his 70th birthday on Friday.

“The key question is whether Russia’s elites and wider society are ready to accompany their president on this journey to hell,” wrote Tatiana Stanovaya, a Russian political scientist at the Carnegie Endowment for International Peace, a US think tank.

Marie Dumoulin, Russia specialist at the European Council on Foreign Relations, warned: “We should not take our dreams for reality. Nobody knows when it will happen, under what circumstances and what will come after Putin.”

“There are tensions within the system, that’s for sure, but it seems to me it’s about internal clans competing for power without challenging Putin’s authority,” she told AFP.

Right now it’s “not that many people attacking him, it’s attacking each other,” Cohen said.