Moscow's rapid loss of more than 2,300 square miles of territory in northeastern Ukraine has raised the prospect that the Russian military is spent as an offensive force for the foreseeable future, which could limit Russian President Vladimir Putin to defending the Ukrainian territory he already holds while leaving him open to additional defeats, according to military analysts.

The situation is a sobering reality for Putin, whose forces barreled into Ukraine on Feb. 24 on a mission to "demilitarize" and "denazify" the country but retreated from Kyiv just over five weeks later to concentrate on expanding control over Ukraine's east through artillery warfare. As Ukrainian forces roll back those eastern gains, Putin faces obstacles in replenishing the battered ranks and degraded equipment of his military to any degree that would allow Russia to again take the initiative on the battlefield.

The result is an opportunity for Ukrainian forces, which despite significant losses of their own, are hoping to make more territorial gains before winter conditions harden battle lines. Further gains by Ukraine — particularly around the southern city of Kherson — would deal additional blows to Russian morale and increase pressure on Putin, who is already facing calls by hard-line Russians to announce a general mobilization that could be politically toxic for his regime.

The rapid collapse of the Russian front around Kharkiv in recent days "reflects the structural problems with manpower and low morale in an overstretched Russian military," said Michael Kofman, a Russian military analyst at Virginia-based research group CNA.

"The Russian military's approach is fundamentally unsustainable," Kofman said. "Russian forces face exhaustion, retention problems and a steady degradation of combat effectiveness."

A "partial mobilization" in Russia could provide a boost looking into next year, Kofman said, but Russia lacks the forces in the short term to defend its territory in the south of Ukraine while also making any meaningful advances in the eastern Donbas region.

Retired Lt. Gen. Ben Hodges, the former commander of U.S. Army Europe, said the Russian military had reached what military theorist Carl von Clausewitz called the "culminating point," or the moment when an attacking force can no longer proceed. Hodges said Ukrainian forces helped bring that about.

"What's happening now is the culmination of a couple of months of really hard work, of planning and preparation by the Ukrainian general staff, to disrupt Russian logistics, destroy command posts, destroy their artillery and ammunition supplies — to weaken them so they would be vulnerable to a counterattack," Hodges said. The key now, he said, is: "Can the Ukrainians sustain this?"

Ukraine's Western partners will continue to send weapons and intelligence to Kyiv to enable Ukrainian forces to keep up the pressure, Hodges said, but it will still be a challenge to maintain the operation with fuel, ammunition and rested personnel without losing momentum. Having so many external partners should help Kyiv, he said.

"The Russians not only have manpower problems and will-to-fight problems, they don't really have any friends," Hodges said. "Iranian drones aren't going to move the needle at all. I am very skeptical of reports of North Korean artillery ammunition coming in and making a difference."

The Ukrainian military's focus will probably shift to Kherson, the occupied city in Ukraine's south, where Russian forces are defending a vulnerable swath of territory on the eastern side of the Dnieper River. Russia has moved elite units into the area to defend the position, which will make the fight difficult for the Ukrainians, analysts said.

"The next thing that Russia will want to do is make sure things don't collapse in Kherson," said Dara Massicot, a Russian military analyst at the Rand Corp. "I think it would be very difficult for them to recover from two rapid collapses in succession."

Massicot said the mounting pressure on Moscow, with separatist proxy fighters starting to mutiny and Russian military units retreating in some cases before engaging in combat, traces back to "the very abusive way that Russia has managed its fighting force."

American officials cast the Russian failures in northeast Ukraine as something that was only a "matter of time," considering the Kremlin's months-long failure to organize, command, equip and sustain its forces on the battlefield — and Ukraine's growing arsenal of weapons from the West.

The Russian military was "riven with all kinds of weaknesses that were not apparent to the leadership and probably should have been" at the outset of their Feb. 24 invasion, according to a senior U.S. defense official, who, like some others, spoke on the condition of anonymity because of the sensitivity of the issue.

"A lot of the key elements of a strong defense are the capabilities of your soldiers, the capabilities of logistics, and command, and we've seen fractures in all of those elements, and they played out in many places over time in the east," the senior U.S. defense official said.

The rapid retreat around Kharkiv has also cost Russia critical equipment that will be difficult to replace. According to preliminary estimates from Jakub Janovsky, a military analyst and contributor to the Oryx blog tally of equipment losses, Russia lost 40 tanks, 50 infantry vehicles, 35 armored vehicles and two jets.

U.S. officials have estimated that Russia has suffered as many as 80,000 casualties since February, including more than 15,000 deaths.

The Russian open-source military analysis group Conflict Intelligence Team, now in Tbilisi, Georgia, estimated losses of equipment and personnel to be so dire that it downgraded the Russian military's fighting ability in Ukraine from "capable of attacking" to "capable of limited defense."

In particular, the Ukrainian successes around Kharkiv revealed the weakness of Russia's 11th Army Corps, based in Kaliningrad, and its vaunted 1st Guards Tank Division, based outside Moscow.

"Previously, we were not sure that the problems known to us, that we gleaned from intercepts, saying there was a lack of working equipment or negligence of commanders [in individual units], have been this systemic," the CIT expert, Ruslan Leviev, said in a Monday briefing. "But now it turned out that the 11th Army Corps was completely incapable of defending the front line."

The CIT said the 11th Army Corps was the main force responding to the Ukrainian counteroffensive but is unlikely to operate independently anytime soon, as it has been depleted following the Ukrainian advance.

The Ukrainian offensive "also revealed that the organizational structure of the 1st Tank Army was completely broken due to a large number of casualties and prolonged participation in hostilities," Leviev said, adding that losing these two formations is "a serious loss for the Russian army."

Russia's 1st Guards Tank Army is considered an elite force, "allocated for the defense of Moscow, and intended to lead counterattacks in the case of a war with NATO," the U.K.'s Defense Ministry said Tuesday in its daily intelligence update.

But CIT said the tank army has suffered massive losses since February, forcing the Russian Defense Ministry to swap service members between various units.

"So instead of independent units within one structure of a division, only fragments remained, and from these fragments, they've been forming other battalion tactical groups, and it all turned into something of a minced salad," Leviev said.

"Russia doesn't have the capacity anymore to regain the positions it lost to Ukraine," Leviev added, but CIT noted that Russia may still prove able to defend its existing positions around Kherson.

The failures on the battlefield have caused problems for Putin among hard-liners at home.

Disgruntled by the way Russia is faring in Ukraine, pro-war Telegram bloggers who boast a huge following, state media figures and even some officials have come out with rare criticism of Putin's decision to not launch a general mobilization and attempt to portray the war as a limited operation.

Sergey Mironov, the leader of A Just Russia party, publicly criticized the lavish Moscow Day celebrations in which Putin took part over the weekend, blessing a new Ferris wheel that reportedly broke down a few hours after the ceremony.

"It's time for a full-scale mobilization! But not a military one but mobilization in our minds," said Mironov, addressing the Russian parliament on Tuesday. "It cannot be that there is a war going on, and the entire country is dancing and having fun. Enough! Only the truth and an honest assessment of what is happening will help us win."

The longtime leader of the Russian Communist Party, Gennady Zyuganov, said that Russia's undertaking in Ukraine can no longer be called a "special military operation," the Kremlin's preferred euphemism for war.

"Over the past two months, the special operation in Ukraine and Donbas has turned into a war. Any war requires a response. First of all, maximum mobilization of forces and resources is required," Zyuganov said.

A few hours later, the party's press secretary backtracked, saying Zyuganov referred to the "mobilization of economy and the political system," not the enlistment of the entire eligible population, suggesting "those who published the news item" should be executed.

Even if Putin were to take the political risk of a general mobilization, it would take months to train and equip new soldiers and many of Russia's battlefield woes would remain unsolved.

"I have some questions about whether the system can even comply at this point with a mobilization order," Massicot said. "Who is going to train or who is going to lead these people? You are going to be relying on reserve officers. What equipment are you going to use?"

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