russian army Security forces on Tuesday dropped an alleged cross border raid The attackers from Ukraine claimed to have killed more than 70 attackers in a battle that lasted about 24 hours, a senior Moscow official said.

Claims of an armed incursion into Russian territory that began on Monday could not be independently confirmed. It was also impossible to say exactly who was behind the attack or what its purpose was.

Disinformation has been one of the weapons of war for almost 15 months.

Moscow blamed the attack on Ukrainian military saboteurs. Kiev described the incident as an uprising by Russian partisans against the Kremlin. It was not possible to reconcile the two versions immediately.

The fighting took place in the Belgorod region, about 45 miles north of the city of Kharkiv in eastern Ukraine.

Russian Defense Ministry spokesman Igor Konashenkov claimed the armed attackers were routed by local troops, airstrikes and artillery fire.

“The remnants of the nationalists were driven back to Ukrainian territory, where they continued to be bombarded until they were completely wiped out,” Konashenkov said, without providing evidence. He did not mention any Russian casualties.

He said four armored fighting vehicles and five pickup trucks used by the attackers were destroyed. Drones and artillery were also used in the attack, local officials said.

Vyacheslav Gladkov, the governor of Belgorod region, said the raid targeted rural areas around the town of Graveron, about 3 miles from the border. He said 12 civilians were injured in the attack and an elderly woman died during the evacuation.

Earlier Tuesday, Gladkov urged evacuated residents to stay put and not return until they received official instructions. He said “counter-terrorism operations” were underway.

While it wasn’t the first time Russia claimed an invasion by Ukrainian saboteurs, it was the first time a counterattack had been carried out for a second day in a row, underscoring the struggle Moscow faces as its incursion into Ukraine has bogged down and embarrassed the Kremlin.

Russian territory and Russian-occupied regions of Ukraine have also been hit by drones and explosions that derailed trains, although officials in Kiev have brushed aside allegations of orchestrating the incidents.

Ukraine said Russian citizens belonging to shadowy groups calling themselves the Russian Volunteer Legion and the “Russian Free Corps” were behind the attack.

Ukraine’s Deputy Defense Minister Hannah Malyar said on Tuesday that Russian dissidents unhappy with the policies of Russian President Vladimir Putin had instigated the attack.

“As we understand it, these are Russian patriots. Those who are really fighting against the Putin regime,” she said.

The Russian Freedom Corps said on its Telegram channel that the goal was to “liberate” the region.

Russian volunteers hinted the attack was over in a Telegram post, adding: “One day, we will stay.”

The Ministry of Defense said it was “highly likely” that Russian security forces were fighting guerrillas at at least three locations in Belgorod.

“Russia faces growing multi-domain security threats across its borders, loss of fighter jets, IED attacks on railway lines, and now direct partisan action,” it said in a tweet on Tuesday.

Russia’s top law enforcement agency, the Investigative Committee, announced an investigation into suspected terrorism and attempted murder related to the incident.

Belgorod officials said earlier this year that they had spent nearly 10 billion rubles ($125 million) on fortifications to protect the region from invasion during the war.

Kremlin spokesman Dmitry Peskov said the raid was “deeply concerning” and that “greater efforts” were needed to prevent such attacks in the future.

Peskov declined to say how many attackers were involved in the attack, nor would he comment on why efforts to suppress the attackers took so long. In a conference call with reporters on Tuesday, he referred the questions to Russia’s Defense Ministry and Federal Security Service (FSB).

Regional Governor Gladkov said authorities had imposed special controls, including checking personal documents and stopping the work of companies using “explosive, radioactive, chemical and biological hazardous substances”.

Russian volunteers claimed to have breached the border in early March. The mysterious group described itself as “a formation of volunteers fighting on the Ukrainian side”. It is unclear whether it has any links to the Ukrainian military. The same goes for the “Russian Freedom” Corps.

The Belgorod region in southwestern Russia, like the neighboring Bryansk region and several others, has seen sporadic spillovers from the war, with its border towns and villages regularly subjected to shelling and drone strikes.