Clad in khaki fatigues, the Ukrainian volunteers lounged on a concrete terrace as dusk swallowed the surrounding fields. Music trickled from a phone, mingling with bursts of laughter — a fleeting ease before what they had been warned would be a “hot night.”

They were members of one of many civilian units guarding the skies around the capital, Kyiv, on a recent Saturday night, their job to shoot down incoming Russian drones using old machine guns supplied by the Ukrainian Army. As they do every night, the volunteers — university professors, builders, salesmen — stood ready at their base in Pereiaslav, a town 50 miles southeast of Kyiv, waiting for the signal to deploy.

At 11:35 p.m., Mykhailo’s phone rang. He picked it up, then shouted, “Let’s go!”

The chase was on.

Mykhailo and the other two members of his crew jumped into a gray pickup parked at the foot of the terrace and sped off, racing through narrow roads into the countryside. They pulled up beside an open field a few minutes later and jumped out. Moving quickly, they set up three tripods — two for machine guns, the third for night-vision binoculars and a laser.

Then, Mykhailo — who, like other crew members in this article, asked to be identified by only his first name for security reasons, according to military protocol — glanced at a tablet set on the pickup’s hood. Its screen lit up with a swarm of red triangles sweeping across a live map of Ukraine; they showed Russian attack drones, several dozen miles away.

“Three heading our way,” said Mykhailo, who is a trade union representative by day. “Let’s wait.”

While Russia intensifies its drone assaults on Ukraine, volunteer crews like the one in Pereiaslav are spending sleepless nights trying to repel them. As the crew deployed last Saturday, Russia launched a record-breaking 472 drones and decoys at Ukraine. This Friday, Russia sent off another swarm of more than than 400 drones and decoys, in addition to nearly 40 cruise missiles and six ballistic missiles at towns and cities across the country, according to the Ukrainian Air Force, in one of the largest barrages of the war.