Belgorod Gov. Vyacheslav Gladkov described the situation there as “extremely difficult and tense” as the attacks destroyed homes and caused civilian casualties, unnerving local people.

Children in particular are being moved to safety, he said on his Telegram channel, adding that about 5,000 children are in camps in safe areas. He said the previous day that around 11,000 people had fled their homes, with about 1,000 staying in temporary accommodation centres.

The surprise Ukrainian charge onto Russian soil that began August 6 has rattled the Kremlin. The daring Kursk operation is the largest attack on Russia since World War II and could involve as many as 10,000 Ukrainian troops backed by armour and artillery, military analysts say. An emergency was declared in Kursk last Saturday.

A Ukrainian Foreign Ministry spokesperson said Tuesday that Kyiv has no intention of occupying the Russian territory it says it is holding. The goal is to stop Russia from firing missiles into Ukraine from Kursk, he said.

It was not clear how or when — or whether — Ukraine would attempt to extricate itself from the ground it has taken. The Ukrainian military claims it controls 74 settlements, believed to be villages or hamlets, in the Kursk region. Russian officials say more than 100,000 people have been evacuated, mostly from Kursk.

Ukraine's 1+1 TV channel published a video report Wednesday it said was from Sudzha, a Russian town about 10 kilometres from the border.

The report showed burnt-out Russian military columns on roads in the area as well as Ukrainian soldiers handing humanitarian aid to local residents and taking down Russian flags from an administrative building.

Russia's predicament is whether to pull troops from the front line in Ukraine's Donetsk region, where achieving a breakthrough is currently a primary war goal for the Kremlin, to defend Kursk and stop the incursion from ballooning.

US President Joe Biden said Tuesday that the developments in Russia are “creating a real dilemma” for Russian President Vladimir Putin. Biden declined to comment further on the top-secret operation until it is over.

The Institute for the Study of War, a Washington think tank, said the incursion is unlikely to shift the dynamics of the war.

“Russian authorities will likely remain extremely averse to pulling Russian military units engaged in combat from (Donetsk) and will likely continue deploying limited numbers of irregular forces to Kursk … due to concerns about further slowing the tempo of Russian operations in these higher priority directions,” it said late Tuesday.

The operation has at least caused embarrassment for the Kremlin as Russian civilians reel from the attack.

A woman in Belgorod told The Associated Press on Tuesday that the Ukrainian shelling had been more intense for about 10 days until Monday, when it was followed by a lull.

The number of people in Belgorod who openly supported the war has decreased following the intensified Ukrainian attacks, the woman told AP, speaking on condition of anonymity because of security concerns.

“When explosions started near the city, when people were dying and when all this started happening before our eyes … and when it affected people personally, they stopped at least openly supporting” the war, the woman said.

Ukraine President Volodymyr Zelenskyy indicated that the Kursk operation is also intended to lift the country's spirits after 900 days of war and rally people by making an emphatic statement about Ukraine's military capabilities.

“Now all of us in Ukraine should act as unitedly and efficiently as we did in the first weeks and months of this war, when Ukraine took the initiative and began to turn the situation to the benefit of our state,” Zelenskyy said in his nightly address Tuesday.

“Now we have done the exact same thing — we have proven once again that we, Ukrainians, are capable of achieving our goals in any situation — capable of defending our interests and our independence,” he said.

Russia's Ministry of Defence said Wednesday it destroyed 117 Ukrainian drones and four missiles over eight of its regions overnight.