Former US general says he is 'even more concerned' about Putin using nukes as Ukraine makes astonishing progress in its counteroffensive

• Western officials and experts have said Putin may use nukes in Ukraine if he gets desperate enough.
• Ukraine is in the middle of a blistering counteroffensive — rapidly recapturing territory.

Over the course of the nearly seven-month war in Ukraine, Western officials and Russia experts have consistently expressed concerns that Russian President Vladimir Putin may resort to using nuclear weapons if he gets desperate enough.

Retired US Army Brig. Gen. Kevin Ryan, a former defense attaché to Russia and senior fellow at Harvard's Belfer Center for Science and International Affairs, said he's now even more worried about the potential for Putin to tap into Russia's sizable nuclear arsenal because of Ukraine's rapid regaining of territory in a lightning counteroffensive that began less than a month ago.

"I have been thinking about the pressure Putin must be feeling to do something dramatic — which causes me to think again about nuclear triggers," Ryan told Insider.

Ryan said that if the occupied territories of Donetsk and Luhansk asked for accession into Russia and were accepted, it would mean "the fighting that is currently going on in Ukraine will suddenly be 'in Russia.'"

After failing to take Kyiv, Ukraine's capital, in the early days of the war, Russia shifted its focus to Ukraine's eastern Donbas region, which is made up of Donetsk and Luhansk. Much of the fighting in the war has been in the Donbas.

The Biden administration has said Russia may attempt to annex Donetsk and Luhansk via "sham referenda." If that happened, there could be immediate ramifications, Ryan said.

"For one, Putin could solve his military-manpower problem because now all the conscripts (35+% of the force) can be used — since it's no longer a war abroad," he said.

"A second development will be that the red lines against fighting on Russian territory will be suddenly crossed," he added. "NATO weapons will be fighting and shooting inside Russia. And most importantly, the Russian state will be under direct attack. And as we know, that is a trigger for using nuclear weapons."

Ryan, who warned as early as March of the potential for Putin to use a "small nuclear weapon," or tactical nuke, in Ukraine, said he's "even more concerned about the possibility of nuclear weapons being used now" than he was earlier.

"If we add the possibility that Russian forces might be losing hard-won territory to Ukrainian forces at the same time, the pressure on Putin to do something dramatic will be enormous," Ryan added.

The former general told Insider he shared these thoughts with senior US officials.

'The response would be overwhelming'

Lately, Russia has ceded significant gains to the Ukrainian armed forces. Ukrainian President Volodymyr Zelenskyy said Ukraine's forces had recaptured over 2,300 square miles in the east and south of the country this month. Until recently, the conflict was widely characterized as a grinding war of attrition with little movement on either side.

Russia has suffered substantial troop losses in Ukraine, which Moscow initially assumed would be conquered swiftly. In August, the Pentagon said it estimated Russia had suffered as many as 80,000 casualties.

As Ukraine pushes Russia's forces into retreat, Russian propagandists on state news channels who have generally offered full-throated support for the war are struggling to continue painting a rosy picture of what's happening on the battlefield. Meanwhile, local lawmakers in Russia have been calling for Putin to be removed from power and charged with treason over the war.

In this context, there are serious concerns about what Putin might do if he feels pushed into a corner. Putin placed Russia's nuclear-deterrent forces on high alert in the immediate aftermath of the invasion, and he's been accused by Western officials of nuclear saber-rattling. Top Ukrainian military officials — including Gen. Valeriy Zaluzhnyi, the commander in chief of the Armed Forces of Ukraine — wrote an op-ed last week that said "limited" nuclear war with Russia could not be ruled out.

But not everyone is convinced that Putin would do something as drastic as using a nuclear weapon to achieve his goals in Ukraine.

"I don't think that Putin would use tactical nukes in this situation — even if he's losing, even if he lost everything in Ukraine," Robert Orttung, a professor of international affairs at George Washington University, told Insider.

"He's obviously going to threaten to use them," Orttung said.

But using such a weapon would "take the war to the next level," and Putin would be "too afraid of what the response would be," he said, adding: "He knows the response would be overwhelming."

"There's a level of uncertainty there. But my best guess would be that he's not going to use them," Orttung said.

If Russia used a nuclear weapon in Ukraine, it could trigger a military response from the US, which could spiral into a direct conflict between Russia and NATO — a 30-member alliance. Multiple NATO members, including the US, have their own nuclear arsenals.

Even if Russia ended up losing in Ukraine or pulled its troops out, Putin could explain it away by blaming NATO and the US to save face, Orttung said, adding: "I think he could do that and still stay in power."

'A red line'

George Barros, a military analyst with the Institute for the Study of War, told Insider the possibility of the Kremlin deciding to use a tactical nuclear weapon or another weapon of mass destruction in Ukraine couldn't be ruled out but said "that risk is low."

"The problem for the Russians is that in order to properly exploit the conditions that are created by a tactical nuclear weapon, you need to have forces that are cohesive, coherent, and with a high level of morale," Barros said, adding: "I don't think the conventional Russian military, at this point, has the capability or the morale to be able to do that."

Russian units deployed in Ukraine "clearly are not in the prime, tip-top shape that they should be in for such an operation," Barros said, and "it would not make sense" for Russia to use a weapon of mass destruction at this time.

Barros said there were also "strategic-level ramifications" for Russia to consider, including that using a weapon of mass destruction in Ukraine would "constitute a red line" for Moscow's Western adversaries.

"I'm sure behind closed doors, the West promised the Kremlin that they would retaliate or respond in an appropriate fashion to such an unprecedented use of that kind of weapon," Barros said.