It has been nearly a month since Russia launched its invasion of Ukraine. Russian troops remain outside Kharkiv and the capital of Kyiv. The past several weeks have seen heavy and brutal combat, cities under siege and civilian casualties, convoys ambushed, Russian tanks and trucks destroyed.

But for a fleet of Ukrainian drones, it’s a target-rich environment.

“We strike at night, when the Russians sleep,” said Yaroslav Honchar, commander of Aerorozvidka, a Ukrainian drone unit, in an interview with The Times of London on Friday.

Russian troops are dispersing into towns and villages in an attempt to avoid artillery strikes, Honchar told The Times of London. However, that doesn’t protect them from Ukraine’s drone operators, who are piloting anything they can get their hands on, from consumer drones found at Wal-Mart, to the now-vaunted Bayraktar TB2 Turkish aircraft. Before the invasion, Ukraine reportedly had around 20 Bayraktar drones, but the country is now using everything up to and including cheap, commercially bought drones to drop munitions on Russian targets.

“In the night it’s impossible to see our drones,” said an Aerorozvidka soldier to the Times of London.

“We look specifically for the most valuable truck in the convoy and then we hit it precisely and we can do it really well with very low collateral damage — even in the villages it’s possible. You can get much closer at night.”

Braggadocio aside, the drones have been able to penetrate what was thought to be a sturdy air defense network.

Drone warfare has been used since the first Russian encroachments in 2014. The Ukrainian drone unit, Aerorozvidka, was started in 2014 by — as improbable as it sounds — model plane enthusiasts. But the unit is now flying up to 300 missions a day, targeting Russian convoys along the frontlines. Often working off the Starlink satellite system, the drones have continued to strike at Russian targets.

“The (TB2s) shouldn’t be making a meaningful impact because they are medium-altitude, slow-flying aircraft with a large electromagnetic signature and a large radar cross-section. And the Russians have very capable air defense systems, so they should be being shot down. The terrain is very open and gives good radar coverage,” said Jack Watling of the Royal Services Institute to the Associated Press.

The skies over Ukraine remain contested, and while neither side has achieved air supremacy, according to a senior defense official, many Russian sorties are never leaving Russian airspace.

As for Ukrainian forces, “they’re being very nimble, very agile in how and when and where they apply air defense – and I’m not just talking about shoulder-fired air defense, short-range, but also long-range, mobile air defenses,” said a senior defense official of Ukraine’s air defense posture on Monday. “They’re being very resourceful in how they’re trying to prevent the Russians from dominating the skies over Ukraine.”

With Russian and Ukrainian forces seemingly deadlocked, though, Ukraine’s drones appear to have no shortage of targets.

“We have an in-house team of military software developers who follow a NATO standard to develop our situational awareness system,” an Aerorozvidka leader told The London Times. He added: “Based on the information we task our 50 teams in the field to either hit the targets identified or provide additional reconnaissance to some special parameters. Or to provide artillery with their eyes — they do the coordination of artillery fire.”