Russian and Ukrainian forces are clashing in Russia’s Kursk region for a third consecutive day, Russia’s Defense Ministry said Thursday.

Russia described it as one of the largest cross-border incursions by Ukrainian forces during the war that started 2½ years ago with Moscow’s invasion of Ukraine along its eastern border with Russia.

But a Defense Ministry statement said the Russian military and border guards have blocked Ukrainian forces from advancing deeper into the Kursk region in southwest Russia. It said the army is attacking Ukrainian combatants who are trying to advance from Ukraine’s Sumy region.

“Attempts by individual units to break through deep into the territory in the Kursk direction are being suppressed,” the ministry said.

The Institute for the Study of War, a Washington-based think tank that has closely monitored the Russia-Ukraine war, said that as of Wednesday, Ukrainian troops had advanced as much as 10 kilometers (6 miles) into Russian territory, although the assessment has not been confirmed.

Ukrainian officials have not publicly commented on the fighting in the Kursk region around the town of Sudzha.

The Kursk region’s acting deputy governor, Andrei Belostotsky, told the state news agency RIA-Novosti, “The enemy has not advanced a single meter. On the contrary, it is retreating. The enemy’s equipment and combat forces are being actively destroyed. We hope that in the near future … the enemy will be stopped.”

Russia’s Defense Ministry said it destroyed Ukrainian aerial drones over the Kursk and Oryol regions.

Alexei Smirnov, the acting governor of Kursk, said Thursday on Telegram that Russian air defenses also shot down several Ukrainian missiles overnight.

Belgorod Governor Vyacheslav Gladkov said on Telegram that Ukrainian drone attacks in two districts damaged an infrastructure facility and a house.

Ukraine’s military said Thursday it shot down two Russian guided missiles and four aerial drones.

The drone intercepts took place over the Kherson, Kirovohrad and Odesa regions, Ukraine’s air force said.

Kirovohrad Governor Andriy Raykovych said on Telegram there was no reported damage from the attacks in his region.

Kherson Governor Oleksandr Prokudin said that in addition to one drone being shot down over the region, Russian forces also shelled Kherson, setting a residential building on fire and damaging several others.

In Dnipropetrovsk, Governor Serhiy Lysak said on Telegram that Russian forces targeted the Nikopol area with drones and artillery, damaging several houses.

Some information for this story was provided by Reuters and The Associated Press.