Russian forces have spread rapidly through Pokrovsk, the city in Ukraine’s east where the warring sides have concentrated their manpower and tactical ingenuity during the past week, in what may be a final culmination of a 21-month battle.Geolocated footage placed Russian troops in central, northern and northeastern Pokrovsk, said the Institute for the Study of War (ISW), a Washington-based think tank.Recommended Stories list of 4 itemsend of listRussia sees control of Pokrovsk and neighbouring Myrnohrad as essential to capturing the remaining unoccupied parts of the Donetsk region.It set its sights on the city almost two years ago, after capturing Avdiivka, 39km (24 miles) to the east.Ukraine sees the defence of the city as a means of eroding Russian manpower and buying time for the “fortress belt” of Kostiantynivka, Druzhkivka, Kramatorsk, and Sloviansk, the largest remaining and most heavily defended cities of Donetsk. Members of the White Angel unit of Ukrainian police officers, who evacuate people from front-line towns and villages, check an area for residents, in Pokrovsk [File: Anatolii Stepanov/Reuters]Russian President Vladimir Putin has demanded their surrender as part of a land swap and ceasefire he discussed with United States President Donald Trump last August. Ukraine has refused.A recent US intelligence assessment said Putin was more determined than ever to prevail on the battlefield in Ukraine, NBC reported.Russia seems to have outmanoeuvred Ukraine by striking its drone operators before they had time to deploy, and cutting off resupply routes at critical points. Advertisement “Operational and tactical aircraft, backed by drones, significantly disrupted the Ukrainian army’s logistics in Pokrovsk,” said Russia’s Ministry of Defence on Friday. It said it had destroyed two out of three bridges across the …