The big battlefield news this afternoon is that Russian troops have made headway in Mariupol, the city in southeast Ukraine that’s been under siege for weeks. They’ve tried to starve the Ukrainians there into surrendering, unsuccessfully. But having weakened the resistance inside Mariupol, Russian forces have reportedly advanced from the outskirts and are now pushing in. “The fighting is already in the city itself,” a source in the mayor’s office told the WSJ.

Look at this map and it’ll immediately be clear why Putin wants Mariupol so badly.

NEW Control-of-terrain #map from @TheStudyofWar and @criticalthreats: #Ukrainian forces conducted a major successful counterattack around #Mykolayiv in the past several days, and #Russian forces continued to secure territorial gains only around #Mariupol on March 18. pic.twitter.com/FB40idbr1R

— ISW (@TheStudyofWar) March 18, 2022

Seizing the city gives Russia control of the entire Ukrainian coastline on the Sea of Azov, from Crimea in the south to the Donbas — Luhansk and Donetsk — in the east. Once they’ve gained that territory, they have multiple strategic options. They could push west to try to finally take Mykolaiv and eventually Odessa, Ukraine’s key port on the Black Sea. Or they could push north towards Dnipro, potentially linking up with Russian forces heading south from Kharkiv if and when that city finally succumbs to Russia’s bombardment. If forces in the north and south can meet in Dnipro, Ukraine’s forces fighting in the east would suddenly find themselves surrounded.

They’re unlikely to surrender, but with Russians on all sides it’d be a matter of time before they’re starved out and overrun. With Russia now in control of the east, they would “gain access to working road and rail lines straight from Russia, which would allow later assaults on Kyiv and Odessa, once they had established large forward supply dumps closer to the targets,” writes Phillips O’Brien, a professor of strategic studies.

You can see Russia’s game plan for total victory coming together, then. Having consolidated control of eastern Ukraine, it could conceivably push northwest towards Kiev and link up with the northern forces already dug in around the capital. Then it’s a matter of laying siege to Zelensky until he surrenders. There’s just one flaw in the strategy: There’s no reason to believe Russia’s tired, demoralized, underfed, and undersupplied army can pull it off. Even if they figured out the logistics needed to make it feasible, they’d continue to take heavy casualties as they work to snuff out Ukrainian resistance in the east.

One estimate is that it would take six months to gain full control of eastern Ukraine. Does this sound like an army that’s in any condition for that sort of grind?

On Thursday, a senior U.S. defense official said Russia’s consideration of bringing in new troops and supplies to reinforce more than 100 battalion tactical groups already in the country indicated that the Kremlin “was beginning to get concerned about the longevity” of its forces in Ukraine. One European diplomat, who spoke to Foreign Policy on condition of anonymity to give a candid military assessment, said Russia has begun to lose enough troops in combat to have a real impact on its ability to carry out offensive operations, and Russian troops on the front lines are beginning to worry about how long they can hold out.

“The Russian troops on the ground definitely think like that. The Russian generals probably think like that,” the European diplomat said. “But whether or not this is getting to Putin or whether he’s listening to this is another matter.”

There are reports circulating of Russian troops begging Ukrainians for food. Good luck keeping those guys in fighting spirits until fall.

Retired Australia general Mick Ryan thinks Putin’s dream of capturing Kiev is already dead. “Facing the Russians in Kyiv are at least 10,000 (and probably many more) defenders. They have had weeks to prepare a very complex set of obstacles,” he writes. “Any Russian encirclement, let alone seizure, of Kyiv will require tens of thousands of Russian soldiers. This would be a very difficult proposition even for a fresh force that is well led. The Russians are neither.” O’Brien agrees:

If they went into more large cities (Kharkiv and Sumy) the casualties might rise. But even if Russian fighting methods improve drastically and they reduce losses to only 1000 a day–they would still lose 60,000 in two more months of attritional limited war.

— Phillips P. OBrien (@PhillipsPOBrien) March 19, 2022

So, the Russian army would be broken and they would not have taken Kyiv or Odessa. Thats the problem with the attritional strategy. Makes sense militarily, however the Russian Army in Ukraine cant do it. Which only makes sense as it was assembled for a quick, easy campaign

— Phillips P. OBrien (@PhillipsPOBrien) March 19, 2022

No one knows what sort of information Putin is getting about the state of his army. Conceivably his aides are still lying to him about what’s possible in Ukraine, or conceivably they’ve told him the truth and he refuses to listen. Either way, he might insist that his forces try to take Kiev only to see them come to ruin. But if he’s sobered up about his capabilities and now grasps that full conquest is out of reach, then I wonder if his new strategy might be partition. If Russia can take Mariupol and Kharkiv and then encircle Ukraine’s eastern forces, maybe that’s when Putin decides to quit while he’s ahead and offers to end the war if Ukraine will concede everything east of Dnipro to Russia.

Ukraine’s western allies will want Zelensky to accept virtually any credible peace offer Putin makes in the name of ending the conflict before it spirals into regional or world war. But that doesn’t mean Zelensky and Ukraine will oblige them:

“There’s no indication on our end that the Ukrainians are suing for peace. They want to fight,” said a senior U.S. official…

“If at the end of this, Putin comes away with anything but a clearly defined loss for him, that would destabilize European and international security unlike anything we’ve seen since the days of the Second World War,” said Jonatan Vseviov, the secretary general of the Estonian Ministry of Foreign Affairs.

But the desire to have Putin feel defeated could also make a middle-ground compromise impossible, officials acknowledged, spurring the Russian leader to keep fighting. European countries would be unlikely to roll back sanctions at the first sign of a peace deal but would wait until there are concrete signs it is actually being implemented and respected, a senior European diplomat said.

Time and world opinion are on Ukraine’s side. Even if Russia gains control of the eastern half of the Ukraine, there’s no reason to believe they could hold it for long so long as the supply of weapons from NATO keeps flowing into the western half. Which raises a question: Is there a scenario in which the U.S. and EU would threaten to cut off those weapons if Ukraine refuses a “fair offer” from Putin? Or are we on the hook for more drones and Javelins so long as Ukrainians are willing to use them?

Maybe the question is moot. Russia may not have the wherewithal to gain control of eastern Ukraine in the first place. They’ve lost ground in the south near Mykolaiv, pushing an assault on Odessa further out of reach. Even the one major southern city they control, Kherson, is susceptible to Ukrainian attack. Putin might conclude that trying to take over the eastern part of the country is too ambitious and opt instead to try to grab what he can in the south. Take Mariupol, then take another shot at Mykolaiv and ultimately Odessa, and then call it a day. That may be the best he can realistically do.