Ukraine’s commander-in-chief said Kiev’s forces controlled 1,000 square kilometers of Russian territory as they carried out their biggest cross-border incursion in two and a half years of full-scale war.
Commander Oleksandr Syrskyi said that Ukraine continued to “conduct an offensive operation in the Kursk region” seven days after it began.
Ukrainian President Volodymyr Zelensky said that Russia brought the war to others and now it is backfiring on Russia.
But Russian leader Vladimir Putin described the offensive as a “serious provocation” and ordered Russian forces to “drive the enemy out of our territory.”
A growing number of people have been evacuated from Russia’s western region for safety reasons, with another 59,000 people being asked to leave on Monday.
The local governor said that around 28 villages in the area had fallen to Ukrainian forces, that 12 civilians had been killed and that “the situation remains difficult”.
Ukrainian troops launched their surprise attack late Tuesday, advancing as far as 18 miles (30 km) into Russia.
The offensive is said to have boosted the morale of the Ukrainian side, but analysts say the strategy brings with it new dangers for Ukraine.
A senior British military source, who asked not to be named, told the BBC that there was a risk that Moscow would be so enraged by the incursion that it would redouble its attacks on civilians and infrastructure in Ukraine.
In remarks broadcast on state television on Monday, President Putin said: “One of the enemy’s obvious goals is to sow discord, conflict, intimidate people, destroy the unity and cohesion of Russian society.
“The main task of the Ministry of Defense is, of course, to drive the enemy out of our territories,” he told a meeting of officials.
The region’s governor said 121,000 people had been evacuated from their homes. He told Mr Putin that about 2,000 Russian citizens remained in areas occupied by Ukrainian forces in the area.
“We know nothing about their fate,” he said.
He advised the population to take shelter from the missiles in rooms without windows and with solid walls.
In Belgorod, the region neighboring Kursk, about 11,000 people were also asked to leave, as Governor Vyacheslav Gladkov told the population of the Krasnaya Yaruga district that the relocation was due to “enemy activity on the border.”
He gave a similar missile warning and told people to take refuge in their cellars.
In his evening speech, the Ukrainian president acknowledged the offensive, saying: “If Putin is so eager to fight, Russia must be forced to make peace.”
“Russia brought war to others, now it is coming home. Ukraine has always wanted only peace, and we will certainly ensure peace,” Zelensky added.
Ukrainian officials said thousands of troops were involved in the operation, a far larger number than the small incursion initially reported by Russian border guards.
An official told AFP news agency that their aim was “to inflict maximum casualties and destabilize the situation in Russia.”
In Russia, there are those who wonder how Ukraine managed to enter the Kursk region. A pro-Russian blogger, Yuri Podolyaka, called the situation “alarming.”
Foreign Ministry spokeswoman Maria Zakharova said a tough response from the Russian military “will not take long.”
Meanwhile, Russia’s ally Belarus said it was stepping up its troops on its border after claiming Ukraine had entered its airspace with drones.