Russia has imposed ‘anti-terror’ measures in western Kursk and in the nearby regions of Bryansk and Belgorod.

Ukraine is bracing for more Russian attacks in retaliation for its cross-border incursion into the Kursk region as Russia was moving in reinforcements, including troops, extra tanks, artillery and rocket systems, the authorities said.

On Saturday, Russia introduced “anti-terrorism measures” in three regions bordering Ukraine, Russian news agencies quoted officials as saying.

The measures by the National Anti-Terrorism Committee in Kursk, Belgorod and Bryansk included the possible evacuation of residents, limits on transport in specific areas, tightened security around sensitive sites, and wiretaps of telephone and other communications, according to RIA news agency.

The statement said the decision, taken by Alexander Bortnikov, the head of the Federal Security Service (FSB), was in response to Ukraine’s “unprecedented attempt to destablise the situation in a series of regions”.

Ukraine launched a surprise offensive in Kursk on Tuesday, in the most significant attack across the border since Russia’s full-scale invasion in February 2022.

Russia’s Ministry of Defence said more troops and munitions were being deployed in the border area near Kursk ahead of a possible counteroffensive, as Ukraine’s advance into Kursk appeared to catch Russia off guard.

Russian President Vladimir Putin has called the incursion a “large-scale provocation” by Ukraine, and the military’s Chief of Staff Valery Gerasimov has promised to crush it.

Russian authorities had already declared a “federal-level” state of emergency in Kursk.

On Friday, a Russian missile struck a supermarket in the Ukrainian town of Kostiantynivka in the front-line Donetsk region, killing at least 14 people and injuring 43 others, Ukrainian officials said.

“Russian terrorists hit an ordinary supermarket and a post office. There are people under the rubble,” President Volodymyr Zelenskyy said on X.

Kostiantynivka lies about 13km (8 miles) from the active combat line in Ukraine’s east.

“No situation on the battlefield can justify targeting civilians,” Ukraine’s Prosecutor General Andriy Kostin said on X, while the regional governor, Vadym Filashkin, said a Kh-38 air-to-surface missile was used in the attack.

There was no immediate comment from Russia, which denies intentionally targeting civilians.

Meanwhile, in Ukraine’s northern Sumy region, volunteers were scrambling to evacuate dozens of residents and their pets, in anticipation of more Russian attacks.

Sumy Governor Volodymyr Artiukh ordered 28 villages evacuated from a 10km (six-mile) zone hugging the border. National police said on Friday that 20,000 people would have to leave.