Ukraine could be facing its biggest loss for months, if the key eastern city of Pokrovsk falls to Russian forces. The battle for this strategic point on a big road and rail artery in the Donetsk region has been going on for well over a year.

If Russia’s Vladimir Putin were able to claim victory there, three years and 10 months into his full-scale war, he would be a step closer to his goal of controlling Ukraine’s entire industrial east – the Donbas, made up of Donetsk and Luhansk regions.

Claims and counter-claims abound, so it is difficult to say. But we do know Russia has amassed tens of thousands of troops in the area, and hundreds of its soldiers have infiltrated the city in the past few weeks, gradually taking over buildings and streets and overwhelming Ukrainian positions.

On Wednesday, Kyiv denied its forces in and around the town had been encircled and maintained they were still involved in “active resistance” and blocking out Russian troops. One Ukrainian regiment said it had cleared the city council building and posted video with the Ukrainian flag.

However, open-source intelligence maps suggest Moscow’s troops are probably occupying large areas of Pokrovsk.

While Ukraine’s official position is that it is holding its own against Russia, military personnel cited by a war correspondent for Ukraine’s Hromadske website said Ukrainian troops were outnumbered and more than 1,000 soldiers were at risk of becoming surrounded.

For its part Russia said it was continuing to advance northwards and thwarting attempts by Ukraine to break its troops out of encirclement. Ukrainian units were trapped in “cauldrons”, the defence ministry said, although several commentators said that was not the case.

Ukraine still had defensive lines to withdraw to and can reset its defence, said analyst Michael Kofman of the Carnegie Endowment for International Peace. “Russian forces lack momentum and the way they have been fighting won’t generate it,” he wrote on X. “Infiltration yields a creeping offensive but can’t yield operationally significant breakthroughs.”

Russia’s military has had its sights trained on Pokrovsk since it captured the eastern city of Avdiivka in February 2024.

Its capture deprived Ukrainian of an important military stronghold in the Donetsk region, but it has since taken 21 months for Russia to advance about 40km (25 miles) to the northwest.

Seizing Pokrovsk would put Vladimir Putin a step closer to his goal of occupying the entire Donbas, even if Russia’s advance this year has been extremely slow.

If Pokrovsk falls, defending its satellite city of Myrnohrad becomes almost untenable and Russian troops would then be able to turn their focus to the battle for Kostyantynivka to the north-east and the rest of the so-called “fortress belt” cities of Druzhkivka, Kramatorsk and Slovyansk.

Pokrovsk is largely deserted now, but it has played a significant strategic role for Ukraine’s military during the full-scale invasion.

Before the war it had a population of some 60,000 people and the city is close to Ukraine’s only mine producing coking coal, which is vital for the steel industry. But there hasn’t been any coal production there since the start of the year, when the town started being evacuated.

Most importantly Pokrovsk is a key road and rail junction in the east, and losing the city could pave the way for Russian forces to advance on the more central Dnipropetrovsk region.

Russian forces are already closing in on the main road to Pavlohrad and Dnipro and to the south-west they have advanced near the Donetsk border with Dnipropetrovsk. Another big road leads to Zaporizhzhia, the capital of another embattled region claimed by Russia.

Putin is understood to have demanded the handover of all of Donetsk as a condition for ending the war.

But even if Pokrovsk falls that does not mean the rest of Donetsk would too.

Ukraine’s Volodymyr Zelensky has long insisted that Russia’s military will have to keep fighting for several more years if it is to have any chance of fully occupying the entire Donbas.

He is not alone. The Institute for the Study of War believes Russia has no means of “rapidly enveloping or penetrating the fortress belt” and says it would likely take several years.

But losing Pokrovsk would be a blow for Ukrainian morale at the start of a winter of Russian attacks on power supplies. It would also come at significant cost to manpower, resources and equipment that have been committed to defending the city.

It might also influence US President Donald Trump’s push for an end to the war and strengthen Moscow’s negotiating position, proving to Trump that Russia is not the “paper tiger” he said it was earlier this autumn.

Although he called off his bid to set up a summit with Putin out of frustration that the Russian leader would not agree to a ceasefire, Russian officials have not given up hope on a deal.

Putin may hope that a Russian success will convince Trump to agree to his demands, even if Ukraine and its European allies reject them.