The Ukrainians battling to stem Russia's assault from the skies

First came the sound of drones. Then a boom that rattled windows.

- Peter Beaumont

Shortly after that, two columns of black smoke rose over the Shebelinka gas processing plant in Ukraine's Kharkiv region. Towering flames threatened storage tanks.

A refinery worker emerged from the site. Russian drones and missiles had struck the plant at 4.30am, he said. For now there was nothing for the fire crews to do but stand back and watch.

It was not just Kharkiv that was hit overnight. Over the course of another night of wearily familiar alarms, Russian air raids struck across the country.

Moscow has intensified its aerial warfare in recent months, launching more than 3,000 drones, 92 missiles and almost 1,400 glide bombs against Ukraine between 5 and 12 October alone.

Near their base in northern Ukraine, air defence troops attached to the territorial brigade reflected on the difficulty of shooting down the Russian drones and missiles that flew through their area, a task they said had become ever harder.

With each air alert - sometimes six times a day - soldiers with pickup trucks and machine guns have 10 minutes to reach their firing points and track the trajectory of the incoming munitions on a tablet.

It is only at a distance of about 1km (0.6 miles) that the gunner can see the target. Then there is less than a minute, sometimes much less, to shoot it down.

"It's really hard. If it is flying at a height of 1,500 metres [4,900ft] - it's like trying to hit the head of a match," said Yury Dovgan, an air defence soldier. "And then the gunner needs to hit the drone's engine or explosive payload." Successes are far fewer than they would like, even with 20 to 60 drones coming daily through their area from Russia's Bryansk region and via Belarus's airspace. But between them and Kyiv are more air defence units.

Dovgan said the stress came not from the maddeningly short window to shoot down the drones, but awareness of what it meant to miss.