"The brave ones try to shoot it down' At the front with Kyiv's drone pilots

At night Sasha and his drone team go in search of the enemy. They drive towards the eastern Ukrainian city of Mariinka, occupied by Russia since December.

- Luke Harding

They unload a large drone and then they fly it across the frontline, above a ghostly landscape of fields and ruined houses, towards the city of Donetsk. The drone carries a deadly arsenal of six grenades.

Sasha, who uses the call sign "Tourist", has bombed more than 100 pieces of Russian military equipment, including tanks, armoured fighting vehicles, selfpropelled guns and ammunition dumps. Russian howitzers are another key target. Recently his special operations unit forestalled a large-scale attack. It spotted seven Russian tanks massed for a dawn raid and disabled two of them. Despite these successes, Ukrainian forces are struggling to hold back the Russians in and around Mariinka and across the Donbas region. After two years of war and last summer's failed Ukrainian counteroffensive, Moscow is on the move. Its troops captured the city of Avdiivka, next to Donetsk, the provincial capital held by the Kremlin since 2014. Russian reinforcements are taking further territory, village by village.

"The Russians have more of everything. Tanks, artillery, human resources and planes," Sasha said, as he conducted a test flight with his bomb-carrying quadcopter. In the distance, black smoke billowed into a white sky. He added: "We have a lot less. And they prepared for this war for a long time.

Unfortunately, we didn't. We can only survive if the west steps up and gives us more weapons." Nearby was a thermal power plant, a reservoir and the small city of Kurakhove. For the first 18 months after Vladimir Putin's invasion, Kurakhove was relatively peaceful. Late last year, however, Russia's army captured the whole of neighbouring Mariinka, edging west. The new frontline runs through the village of Heorhiivka and is four miles from Kurakhove's outskirts.