Ukrainian troops pose for a photo in Lyman, Ukraine, in this picture released on social media, October 1, 2022. Courtesy of Oleksiy Biloshytskyi/via REUTERS

Ukraine on Sunday claimed full control of the eastern logistics hub of Lyman, Kyiv’s most significant battlefield gain in weeks, providing a potential staging post for further attacks to the east while heaping further pressure on the Kremlin.

The stinging setback for Russian President Vladimir Putin came after he proclaimed the annexation of four regions covering nearly a fifth of Ukraine on Friday, an area that includes Lyman. Kyiv and the West have condemned the proclamation as an illegitimate farce.

“As of 1230 (0930 GMT), Lyman is fully cleared,” Ukrainian President Volodymyr Zelenskiy said in a short video clip on his Telegram channel. “Thank you to our troops … Glory to Ukraine!”

Russia’s defense ministry said on Saturday that it was pulling troops out of the area “in connection with the creation of a threat of encirclement.”

It did not mention the city in its daily update on fighting in Ukraine on Sunday, although it said Russian forces had destroyed seven artillery and missile depots in the Ukrainian regions of Kharkiv, Zaporizhzhia, Mykolaiv and Donetsk.

Russian forces captured Lyman from Ukraine in May and had used it as a logistics and transport hub for its operations in the north of the Donetsk region. Losing it is Russia’s largest battlefield loss since Ukraine‘s lightning counteroffensive in the northeastern Kharkiv region last month.

Serhiy Gaidai, governor of the Luhansk region that neighbors Donetsk, said control over Lyman could prove a “key factor” in helping Ukraine reclaim lost territory in his region, whose full capture Moscow announced in early July after weeks of grinding advances.

Britain’s Ministry of Defense described Lyman as operationally important as it commanded a key road crossing over the Siverskyi Donets River, behind which Russia has been attempting to consolidate its defenses.

Russia likely experienced heavy casualties during the withdrawal, the ministry said in a statement. Russia had 5,000 to 5,500 troops in the city before the Ukrainian attack, a spokesperson for Ukraine‘s eastern forces said on Saturday.

The areas Putin claimed as annexed – the Donbas regions of Donetsk and Luhansk plus Kherson and Zaporizhzhia in the south – form a swath of territory equal to about 18% of Ukraine‘s total surface land area.

“Over the past week, the number of Ukrainian flags in Donbas has increased. There will be even more a week’s time,” Zelenskiy said on Saturday in an evening address.

RUSSIAN ANGER

The battlefield setbacks have triggered a fresh wave of criticism within Russia of how its military operation is being handled. Britain’s defense ministry said that was likely to intensify with further setbacks.

Putin ally Ramzan Kadyrov, the leader of Russia’s southern Chechnya region, on Saturday called for a change of strategy “right up to the declaration of martial law in the border areas and the use of low-yield nuclear weapons.”

Other top officials, including former President Dmitry Medvedev, have suggested Russia may need to resort to nuclear weapons, but Kadyrov’s call was the most urgent and explicit. Washington says it would respond decisively to any use of nuclear weapons.

The United States, whose military aid is widely seen as crucial to the counteroffensive successes, hailed the latest Ukrainian gain.

“We’re very encouraged by what we’re seeing right now,” US Defense Secretary Lloyd Austin said on Saturday, telling a news conference that Lyman’s capture would create new problems for Russia’s military.

Austin noted that Lyman was positioned across supply lines that Russia has used to push its troops and material down to the south and to the west, as the Kremlin presses its more than seven-month-long invasion of Ukraine.

“Without those routes, it will be more difficult. So it presents a sort of a dilemma for the Russians going forward.”

Pope Francis on Sunday made an impassioned appeal to Putin to stop “this spiral of violence and death” in Ukraine, saying the crisis there was risking a nuclear escalation with uncontrollable global consequences.

In an address to thousands of people in St. Peter’s Square, Francis also to Ukrainian President Volodymyr Zelenskiy to be open to any “serious peace proposal.”

Zelenskiy said on Friday that Ukraine would not hold peace talks with Russia while Putin was still president.

“Clearly, with this Russian president (that) is impossible. He does not know what dignity and honesty are. Therefore, we are ready for a dialogue with Russia, but with another president of Russia,” Zelenskiy said.