Russia said on Wednesday that Ukrainian troops in Pokrovsk and Kupyansk were surrounded and must surrender or they have no chance of survival, Reuters reported.
Russia has been trying to capture Pokrovsk, dubbed the "gateway to Donetsk", by 2024 as part of a bid to seize the entire Donbas region, of which Ukrainian forces still control about 10%, or 5,000 square kilometers.
In contrast to the frontal attacks that Russian forces have used against other cities, Russia has used evasive maneuvers to encircle Ukrainian forces in both Pokrovsk, and in Kupyansk, as small, highly mobile units and drones disrupt logistics and wreak havoc behind Ukrainian lines.
Russia's tactics in both places have created what Russian military bloggers have called a gray zone of ambiguity, where neither side has full control of the territory but is extremely difficult for the Ukrainian side to defend.
Battlefield maps show that Russian forces are several kilometers from completely encircling Pokrovsk, known in Russia as Krasnoarmeysk, controlling a significant part of Kupyansk and advancing along the main road to the city.
The Russian Defense Ministry directly refuted Ukrainian President Volodymyr Zelensky's statement on Monday that Ukrainian forces were trying to clear what it said were only 60 Russian soldiers in Kupyansk.
It said Ukrainian units were trapped in what it described as "boilers", and that their position is deteriorating rapidly as Russian forces advance, "leaving no chance for Ukrainian servicemen to escape except through voluntary surrender".
Nearly four years after the start of Europe's deadliest war since World War II, Russia is trying to seize all of Donbas and is advancing into the Kharkiv and Dnipropetrovsk regions of eastern Ukraine.
The Russian military claims it now controls over 19% of Ukraine, or about 116,000 square kilometers (44,800 square miles). Pro-Ukrainian maps show that Russia has seized over 3,400 square kilometers of Ukrainian territory so far this year.