Fifteen months ago, Russian leaders ordered tens of thousands of soldiers across the border in the first wave of their invasion of Ukraine. They saw their enemies come at them in what they say is one of the biggest incursions of the war. But on Tuesday, they said they repelled the border attack and that their forces killed more than 70 "saboteurs."

Defense ministry officials said armored vehicles with "Ukrainian nationalists" attacked the region of Belgorod on Monday. They say their forces fought back, surrounded some enemy fighters, and drove the "remnants" back to Ukraine.

On Tuesday, Security Council Deputy chairperson Dmitry Medvedev said, "The question is: what should we do with them? They must be exterminated like rats, not even captured."

Two groups have claimed responsibility for the incursion. Both describe themselves as Russian fighters. They said they are working inside their country to overthrow President Vladimir Putin.

Ukrainian officials denied any involvement. They have cast the attack as a sign of internal division.

Senior Ukrainian military officer Roman Kostenko said, "Those groups have their own task: to destroy Putin's army. We have no intention of claiming Russian territory."

He added that Ukrainians are simply focusing on recapturing their own land.