Ukraine’s counteroffensive has made significant progress in the past week, the Russian Defense Ministry announced Saturday that it will withdraw its troops from two areas in the Kharkiv region in eastern Ukraine.

The news comes days after Ukraine made apparent progress south of the country’s second-largest city, Kharkiv, in what could be the Ukrainian army’s biggest success on the battlefield as they thwarted Russia at the start of the war Attempt to seize the capital, Kyiv. nearly seven months of war.

“These days, the Russian army is showing the best it can do – showing it,” Ukrainian President Volodymyr Zelenskyy said in a video released from his office Saturday night. “And, of course, it was a good decision for them to run.”

Russian Defense Ministry spokesman Igor Konashenkov said troops would be regrouped from the Baraklya and Izyum regions to the eastern Donetsk region. Izyum is the main base for Russian troops in the Kharkiv region, and earlier this week, social media videos showed residents of Baraklia cheering as Ukrainian troops moved in.

Konashenkov said Russia’s move was “to achieve the stated goals of a special military operation to liberate Donbass,” the eastern part of two separatist regions that Russia has declared sovereignty over.

Claims to withdraw troops to focus on Donetsk are similar to Russia’s rationale for withdrawing troops from the Kyiv region when it failed to capture the capital earlier this year.

Igor Girkin, a Russian and an early leader of the Moscow-backed separatist uprising in Donetsk in 2014, scoffed at the notion that the withdrawal was strategic. On the messaging app Telegram, he bluntly called it “an excellent move to transfer the cities of Izyum, Baraklia and Kupiansk to respected Ukrainian partners (apparently within the framework of the plan, and even in advance).”

Earlier on Saturday, Ukrainian officials claimed significant progress in the Kharkiv region, saying their forces had cut off vital supplies to Izyum.

Foreign Ministry spokesman Ole Nikolenko also said the army had recaptured Kupiansk, a town along the main supply route to Igyum that has long been concentrated on the Russian front and heavy artillery and other the location of the battle. Nikolenko tweeted a photo showing soldiers standing in front of a government building in what he said was a government building in Kupiansk, 73 kilometers north of Izyum.

Hours later, the Ukrainian Security Service released news that the troops were in Kupiansk, further suggesting it had been detained. The military did not immediately confirm access to the town, a railway hub that Russia seized in February.

Video on social media appeared to show Ukrainian troops at a roadside checkpoint on the outskirts of Izyum. A large statue with the name of the city can be seen in the image. The Ukrainian army does not recognize control of the city.

Britain’s Ministry of Defence said on Saturday it believed Ukrainian forces had advanced as far as 50 kilometers south of Kharkiv, and described Russian forces around Izyum as “increasingly isolated”.

“The Russian army is likely to be caught off guard. The area is only lightly controlled and Ukrainian forces have captured or surrounded several towns,” the British military said, adding that the loss of Kupiansk would greatly affect Russian supply lines.

The Washington-based think tank, the Institute for War Studies, also cited Ukraine’s huge gains, estimating that Kyiv had captured about 2,500 square kilometers in the eastern breakthrough. The institute said it appeared “disorganized Russian troops were[being]trapped in Ukraine’s rapid advance,” citing social media images of apparently Russian prisoners captured in Izyum and surrounding towns.

The same report said Ukrainian forces “could destroy Russian positions around Izyum if they cut off Russian ground lines of communication north and south of the town”.

The head of the Russian-appointed local administration, Vladislav Sokolov, said on social media that Izum authorities had begun evacuating residents to Russia.

The fighting in eastern Ukraine took place amid an ongoing offensive around Kherson in the south. Analysts believe that Russia may have sent soldiers from the east to reinforce the latter, giving the Ukrainians a chance to strike a weakened front.

Ukrainian Defense Minister Oleksii Reznikov told Ukrainian television channels that the Russian troops in the region had no food or fuel as Kyiv cut off their supply lines.

“It’s going to be like an avalanche,” he said, predicting Russia would back down. “A line of defense will falter and collapse.”

The Ukrainian military was more cautious, claiming it seized “more than 1,000 square kilometers” from pro-Kremlin forces this week. “In some areas, Wehrmacht forces have penetrated enemy fortifications to a depth of 50km,” it said, in line with the UK’s assessment, but gave no geographic details.

Kyiv officials have been tight-lipped about plans for a counteroffensive for weeks, urging residents not to share information on social media.

However, Zelensky said on Friday that since the start of the counteroffensive, troops had recaptured more than 30 settlements in the Kharkiv region.

Elsewhere, Ukraine’s emergency services reported that a 62-year-old woman was killed in a Russian missile attack in the Kharkiv region and her home was razed to the ground overnight.

Ole Sinehubov, the governor of Ukraine’s Kharkiv region, has accused Moscow of an onslaught of re-occupied settlements. Five civilians were hospitalized in the Igyum region and nine were injured elsewhere in the region, he said by telegram.

In the embattled Donbass, Ukraine’s governor said overnight Russian shelling near the city of Bakhmut caused civilian casualties, a key target of Russia’s stalled offensive. Two people were killed and two wounded in Bakhmut and the neighbouring village of Yahidne, Pavlo Kyrylenko said on Telegram.

In the Russian-controlled city of Enehodar, home to Europe’s largest nuclear power plant, power and water have been restored after a four-day blackout due to the explosion, Ukraine Mayor Dmytro Orlov said.

Enerhodar and its Zaporozhye nuclear power plant have been shelled several times in recent weeks, perpetrated by Russia and Ukraine. The shelling has raised concerns about radiation leaks at the plant, which has been cut off from external power; the facility is forced to rely on power from its only working reactor for system cooling and other safety measures.

Workers at the factory helped restore power to Enerhodar, Orlov said, but it was unclear whether the power was coming from the factory or a nearby thermal power station.

Also on Saturday, German Foreign Minister Annalena Berbock made an unannounced visit to Kyiv and said Europe would not tire of helping Ukraine, despite attempts by Russian President Vladimir Putin to increase pressure by withholding energy supplies .

Berbock said Germany would assist Ukraine in finding and clearing mines and other unexploded ordnance left by Russian troops in areas they were repelled.

Despite Ukraine’s progress, U.S. Secretary of State Anthony Blinken and NATO leaders warned on Friday that the war could drag on for months. Blinken said the conflict was entering a critical period and urged Ukraine’s Western backers to remain supportive through what could be a difficult winter.

– Associated Press