KYIV, Ukraine >> A Ukrainian drone struck a campus belonging to Russia’s National Guard Sunday in the Russian region of Chechnya, as Kyiv continues to strike back after a mass air attack from Moscow.

Footage on social media showed a drone swooping low over the Chechen capital, Grozny, some 800 kilometers (500 miles) southeast of the front line in Ukraine, before exploding. No casualties were reported.

Chechen leader Ramzan Kadyrov confirmed that the drone had hit a site belonging to the Akhmat Grozny riot police battalion, and said that two other drones had been shot down by air defenses.

Kadyrov pledged revenge on Ukrainian forces and said he had ordered a missile strike against military facilities in Kharkiv in retaliation for the attack. The claim could not be independently verified.

Russia’s Defense Ministry said Sunday that it had shot down 15 Ukrainian drones overnight in the country’s Kursk and Belgorod regions, as well as over the Black Sea. It did not mention the Grozny attack.

An official in Ukraine’s security service also told the AP on Sunday that Ukrainian intelligence services had conducted a special operation to sever Russia’s logistic fuel supply routes from Ukraine’s annexed Crimea to occupied Zaporizhzhia.

The operation, which took place Saturday, destroyed a locomotive and 40 tanker cars, the security official said. A sabotage operation reportedly blew up railway tracks while the train was moving, before HIMARS rocket launch systems joined the attack.

“As a result, a key railway branch used to supply Russian troops was put out of service for an extended period,” said the official, who asked to remain anonymous in order to share sensitive information.