Ukraine’s top military leader has announced that Kyiv’s forces now control 1,000 square kilometers of Russian territory as they advance in their largest cross-border operation in two and a half years of full-scale war.

Commander Oleksandr Syrskyi reported that Ukraine is actively conducting an offensive in the Kursk region, a week after the operation commenced.

President Volodymyr Zelensky remarked that while Russia had brought the war to others, it is now being fought on Russian soil.

In response, Russian President Vladimir Putin condemned the offensive as a “major provocation” and has commanded Russian troops to “expel the enemy from our territory.”

A growing number of people have been evacuated from the western Russian region for their safety, with a further 59,000 told to leave.

The local governor said some 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 last Tuesday, advancing up to 18 miles (30km) into Russia.

The offensive is said to have boosted morale on the Ukrainian side, but analysts say the strategy brings fresh dangers to Ukraine.

A senior British military source, who asked not to be named, told the BBC there was the risk that Moscow will be so angered by this incursion that it could redouble its own attacks on Ukraine’s civilian population and infrastructure.

In remarks broadcast on state television, President Putin stated on Monday: “A clear objective of the adversary is to incite discord, create unrest, intimidate citizens, and undermine the unity and cohesion of Russian society. The primary goal, of course, is for the defense ministry to expel the enemy from our territories,” he told a gathering of officials.

The governor of the affected region reported that 121,000 people had been evacuated from their homes and informed Putin that approximately 2,000 Russian citizens remained in areas controlled by Ukrainian forces. “We are unaware of their current situation,” he said. He advised people to seek shelter from missiles in rooms without windows and with sturdy walls.

In Belgorod, a neighboring region to Kursk, about 11,000 people were also advised to evacuate. Governor Vyacheslav Gladkov informed residents of the Krasnaya Yaruga district that the move was due to “enemy activity on the border.” He issued a similar warning about missiles and recommended taking cover in basements.

In his nightly address, Ukraine’s President Zelensky acknowledged the ongoing offensive, asserting: “If Putin is so eager to fight, then Russia must be compelled to make peace. Ukraine has always sought only peace, and we will surely secure it.”

Ukrainian officials have indicated that thousands of troops are involved in the operation, significantly more than the small incursion initially reported by Russian border guards. An official told AFP that the aim was to “inflict significant damage and destabilize the situation in Russia.”

During a meeting with Zelensky in Kyiv on Monday, US Senator Lindsey Graham praised the cross-border operation as “brilliant” and “bold,” and urged the Biden administration to provide Ukraine with the necessary weapons.