Air traffic at 13 airports in southern Russia has been suspended after drones struck a building at a local air navigation center in Rostov-on-Don, the Russian transport ministry said.

The strike led to the suspension of flights to and from airports in Astrakhan, Vladikavkaz, Volgograd, Gelendzhik, Grozny, Krasnodar, Makhachkala, Magas, Mineralnye Vody, Nalchik, Sochi, Stavropol and Elista.

In a post on its official Telegram channel, the ministry said: “The regional air traffic control center in Rostov-on-Don, which manages air traffic in southern Russia, has been temporarily adjusted due to the Ukrainian drone strike … personnel are safe, and equipment is being assessed” to determine whether it can be restored.

Russia’s government and the Federal Air Transport Agency, together with airlines and airports, are adjusting schedules, the ministry added.

According to Russian news agency Tass, flag carrier Aeroflot is delaying departures and rerouting or canceling flights due to the disruption. The airline said international flights from other airports continue to operate.

Explosions were also reported on Friday at an oil refinery in Yaroslavl, northeast of Moscow, and in the capital.

The strikes followed statements by Ukrainian President Volodymyr Zelenskyy that Kyiv no longer considers itself bound by the unilateral truce declared by Russia ahead of its Victory Day parade on Saturday, after accusing the Kremlin of violating the ceasefire.

Zelenskyy confirmed the latest Ukrainian attack on the Yaroslavl refinery, which he described as “long-range sanctions,” according to Ukrainska Pravda.