An anti-Putin group of Russians aligned with the Ukrainian military claimed responsibility for the attack in the southwestern Russian region of Belgorod, where Moscow said it was fighting a group of saboteurs.
Shelling damaged an administrative building, several residential buildings and a kindergarten, according to regional governor Vyacheslav Klatkov, who said there were no casualties.
In a Telegram post, groups calling themselves the “Freedom of Russia Legion” and the “Russian Volunteer Corps” said they had “liberated” a settlement in the Belgorod region, which borders Ukraine.
A Ukrainian official acknowledged an operation in the area but insisted they were acting independently.
“We can confirm that the operation was carried out by Russian citizens,” Andriy Yusov, a representative of Ukraine’s security intelligence agency, told CNN.
The units were “part of the Security and Defense Forces” while in Ukraine, but independent of Kiev when they were not: “In Russia they operate as independent entities.”
Kremlin spokesman Dmitry Peskov said Kremlin forces were working to take out a “sabotage and espionage group,” state media TASS reported.
According to CNN’s Sam Kiley, the situation in Belgorod marks the “first time” that Ukrainian-aligned forces have launched a “cross-border ground operation against Russian targets.”
“It’s on a significant scale, and it’s causing considerable consternation among local officials, if not at the level of the Kremlin,” Kiley told CNN’s Lynda Kinkade on Connect the World.
A helicopter hovers over Russia’s Belgorod region, a battleground between Russian renegades and pro-Kremlin troops amid the war in Ukraine.
At least eight people were injured in the attacks, but there were no civilian deaths in Belgorod, regional governor Klatkov said.
“The situation is very tense. A sabotage and reconnaissance team, the Ministry of Defense and all law enforcement agencies have entered the territory to carry out combat operations to protect our country,” Kladkov said in a live broadcast address on Monday.
Kladkov said the Belgorod government is “completing a house tour of border villages” to ensure the safety of local residents.
He added that “most people have left the area” and the local government is providing assistance to those who do not have the opportunity to leave on their own.
He also noted that the head of the district, Gennady Ivanovich Bondarev, was working with the Emergencies Ministry and the police to evacuate people.
Russian troops, the Border Service, the National Guard and the FSB are “taking the necessary steps to eliminate the enemy,” he said earlier.
Air defenses shot down an unmanned aerial vehicle (UAV) in the area, Gladkov said, adding that there were no casualties and that Russian officials were checking for any damage on the ground.
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Alexei Baranovsky, a representative of the Kyiv-based Russian Anti-Arms Political Center — the political wing of Russia’s Freedom Brigade — told CNN the operation began Sunday night and that the fighting “continues.”
He did not specify the number of fighters who crossed the border into Russia.
Baranovsky said the group wanted to “liberate our motherland from Putin’s tyranny.”
In a Telegram post, the groups claimed to have “completely liberated the settlement of Kosinka, Belgorod region. [The] The first groups entered Graveron.”
In a separate incident on Monday evening, Russia’s Freedom Legion posted a video on Telegram showing a blue and white flag flying over Moscow State University, known as the Flag of Free Russia.
Other videos released by the group show another Russian opposition flag flying in different parts of the Russian capital.
The group has not directly claimed responsibility for the incidents and CNN has not been able to independently verify the reports.
The Freedom of Russia Legion numbers a few hundred tough, battle-hardened Russian volunteers fighting alongside their own people as part of the Ukrainian armed forces.
A member of the Caesar group. He is a former teacher, father and wife living in Kyiv. He told CNN Last year he dedicated his life to bringing down Russian President Vladimir Putin and marching in Red Square and the Kremlin.
He is a devoted member of the Orthodox Church and nostalgic for the pre-Soviet Tsarist era. His unit is well equipped with modern armored vehicles, gun sights and latest automatic weapons.
Legionnaires themselves admit that they are often treated with suspicion by Ukrainian soldiers, but are confident that they will overcome them with bravery on the battlefield.
Their apparent penetration of the border, which is often used by Russian mortar groups and artillery to launch attacks into Ukraine, will help further cement their reputation.
It also serves as part of an ongoing psychological operation aimed at undermining support for the war in Russia and the fighting spirit of Russian soldiers – implying that they could be attacked at any moment, even by their own countrymen.
Peskov, the Kremlin’s spokesman, said: “Russian forces are working to expel the Ukrainian subversive and espionage group from the Russian Federation and destroy it. There are sufficient forces and means,” he told reporters.
He was referring to Bagmut, which has become increasingly important in the conflict as Russian forces battle to capture the eastern Ukrainian city, failing to make progress elsewhere.
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