- Russia has taken back some of the territory that Ukraine seized in Kursk.
- Warfare experts said it was territory that's easiest to take back and it will get harder for Russia.
- Ukraine can strategically pick where to defend but still has a big challenge ahead.
Russia's retaking territory in Kursk, but efforts to drive the Ukrainian forces out of the country will likely only get more difficult.
Ukrainian troops invaded the Kursk region in southwestern Russia in August, and at one point, they held roughly 500 square miles of Russian territory. Russia's response to the shock assault was slow, but a larger effort to drive the Ukrainians out is now underway.
William Alberque, a warfare expert at the Stimson Center, told Business Insider that Russia has been reducing Ukraine's hold of "the easy parts to take back," adding that "they'll have a much harder time with the rest of the Ukrainian salient, which is still very large."
Ukrainian troops are "giving up the open land and open forests, the territory that's very difficult to defend and moving back."
He added, "then it'll be up to Ukraine what to do next."
Like other war watchers, Matthew Savill, a military strategy expert at the Royal United Services Institute think tank and a former intelligence analyst at the UK Ministry of Defence, told BI that, so far, Russia had taken back "the easier parts."
Ukraine has been able to slow the Russian advance through steps like blowing up bridges critical for moving in troops, weapons, and ammunition.
Still, Russia has taken back 46% of what Ukraine once held in Kursk, the US-based Institute for the Study of War said in an update earlier this month, citing visual evidence.
A harder fight for Russia
Ukrainian forces have options for defending and moving in Kursk that typically only Russian soldiers fighting in Ukraine have had in this war.
They have flexibility. Unlike at home, where Ukraine fights to defend all of its territory, inside Russia, it can be more mobile and strategically give up some land to better defend the areas it can really hold or wants to more.
Michael Bohnert, a warfare expert at RAND Corporation, told BI Ukraine doesn't have to defend Russian cities. "You just fight where it's advantageous and pull back when it's not. And that's a really efficient way of fighting," he said.
It is not clear how much of the territory that Russia took back was deliberately given up by Ukraine, but experts say they never expected Ukraine to hold all of the territory that it it seized.
"While someone might look at the recent advances and say they're big, I would also say it's because Ukraine just took so much territory, more than they even intended to defend," Alberque said.
"So it's very easy now for Ukraine to do some sort of fighting retreats and seed territory that they could never legitimately hold," he explained.
Russia's initial reaction to Ukraine's unexpected incursion was slow and messy. Russian President Vladimir Putin froze at first but eventually put the FSB — Russia's security and intelligence agency — in charge of a complicated response involving other groups.
That time gave Ukraine a certain defensive advantage, experts said, though it is unclear to what extent Ukraine leveraged that opportunity.
"I've always thought that if Russia attacked much, much more quickly against the Ukrainian salient, Ukraine would've withdrawn more quickly," Alberque said.
Savill said Russia's botched response has enabled the Ukrainians "to hold on for a lot longer than they might've expected," which "should give them an opportunity to do some serious digging in."
No easy fight for Ukraine
Ukraine still faces significant challenges in Kursk. Russia's military is larger than Ukraine's, which means that the more resources Russia uses, the harder it will be to defend.
Russia has not focused a huge amount of its efforts onto Kursk, instead focusing on attacking Ukraine's east, continuing to advance, but there are indications it may be preparing to use as many as 10,000 North Korean troops in Kursk.
Ukraine has to make calculations about what sort of resources and losses it wants to have in Kursk when its ultimate priority is taking back its own country from Russia.
It may decide that defending all or much of Kursk is ultimately not worth it, and Alberque said that Kursk is "very, very hard to defend in terms of geographic outlay."
Ukrainian President Volodymyr Zelenskyy said his forces took territory in Kursk because it could help it negotiate with Russia and create a buffer zone along Ukraine's border. Warfare experts said Ukraine was likely trying to also boost the morale of their troops and to send a message to Western allies whose support was waning.
The Kursk incursion also gives Ukraine a chance to bleed the Russians and draw some Russian forces away from the front lines in Ukraine. But Zelenskyy said Ukraine's plan was not to hold the territory forever.
Savill said the Kursk invasion has "value" by helping Ukraine's efforts in its own country and may have prevented more Russian troops from going into Ukraine through the Kursk region
But he said it has not been "a hammer blow to the Russian war effort," and Russia taking back some territory makes it less effective for Ukraine as a bargaining chip.
It did manage to shake up the war for the first time in months and allow Ukraine to finally regain the initiative in at least one sector of the conflict.
But given the unknowns about each side's next steps and the resources they are willing to commit, Savill said that ultimately, "it might take weeks or months to work out the value."