President Volodymyr Zelensky said his country’s surprise attack on Russia’s Kursk was intended to remind Vladimir Putin that his decision to invade Ukraine has consequences.

Mr Zelensky praised the Ukrainian army for its ability to “surprise” and achieve results without directly addressing the situation in the Russian border region.

“Russia brought war to our country and should feel what it has done,” Zelensky said. “Ukrainians know how to achieve their goals. And we did not choose to achieve our goals through war,” he added.

Speaking at an event to launch a new digital app designed to reduce bureaucratic red tape for the military, he said: “Everyone can see that the Ukrainian army knows how to surprise. And how to get results.”

“This is evident on the battlefield, where our soldiers not only withstood the overwhelming power of the occupiers, but also destroyed them in the necessary way to protect Ukraine – our state and our independence,” he said.

Russia claims that at least 1,000 Ukrainian soldiers entered its territory in Kursk, carrying out Ukraine’s largest and boldest attack on Russian soil to date.

The Ukrainian military has not commented publicly on the attack and initially appears to have pursued a strategy of strict silence about activities on Russian territory.

Rescue teams are still digging through the rubble of an attacked supermarket in the Donetsk region, where at least 10 people were killed in a Russian attack.

This afternoon, firefighters were seen battling the fire in the ruins of Kostiantynivka.

President Volodymyr Zelensky condemned the attack, saying: “Russia will be held accountable for this terror and we will do everything to ensure that the world continues to stand by Ukraine, supporting our defense and saving the lives of our people.”

Hundreds of Signal users in Russia reported outages on Friday in the messaging app, a secure communications tool used by up to a million Russians to encrypt messages and conversations.

Internet service monitoring sites have recorded more than 1,500 complaints about Signal, most of them from users in Moscow and St. Petersburg. However, users reported that Signal worked normally when accessed through a VPN or used in the built-in censorship bypass mode.

“This indicates precisely a blocking of the messenger in Russia, and not a technical problem on the Signal side,” Mikhail Klimarev, author of the Telegram channel “For Telecom,” told Reuters.

Signal did not immediately respond to a request for comment. Russia’s internet regulator Roskomnadzor also did not immediately respond to a request for comment.

Three people from Moscow and the Krasnodar region told Reuters that it was also not possible to register a new account with Signal without a VPN. When entering a mobile phone number, the service displayed the message “server error”.

Klimarev said it was the first attempt to block the messenger in Russia.

To mark the fourth anniversary of the “sham election” that sparked mass protests in the country, Britain has imposed new sanctions on Belarusian companies and penal colony commanders.

The sanctions announced by the Foreign Ministry targeted three commanders and a former commandant of penal colonies. Two machine tool manufacturers that export goods to Russia for military-industrial purposes and a company operating in the Belarusian defense sector were also sanctioned.

The State Department cited the crackdown on civil society after Alexander Lukashenko claimed victory in disputed elections in Belarus in August 2020. It also said the sanctions were a response to “human rights violations and continued support for Russia’s illegal invasion of Ukraine.”

The UK also announced planned funding of £2.5 million to support the survival of human rights and civil society issues in Belarus in the face of ongoing political pressure.

A Russian missile attack hit a supermarket in the Donetsk city of Kostiantynivka, killing at least ten people and injuring 35 others, Ukrainian officials said.

The attack sparked a fire that has been extinguished, the interior minister said. Pictures and videos posted by officials show thick black clouds of smoke rising from the destroyed building.

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

Rescue workers continued to search for survivors in the rubble, he added. The region’s governor, Vadym Filashkin, initially said Russia had used artillery but later said the attack was carried out by an X-38 air-to-ground missile.

Russian authorities have declared the situation in the Kursk region a “federal state of emergency,” four days after hundreds of Ukrainian troops poured across the border in what is believed to be Kyiv’s biggest attack on Russian soil since the war began.

Acting Kursk Governor Alexei Smirnov said on Telegram: “The operational situation in the Kursk region remains difficult.”

Social services and civic associations are helping people forced to leave their homes by the fighting, he said. The latest Russian number of evacuees in Kursk was 3,000.

The Russian Defense Ministry said it would deploy additional troops to the Kursk region this week in response to a large-scale Ukrainian incursion.

Columns of Grad multiple rocket launchers, artillery and tanks have advanced into the area from which Ukraine launched its attack, the Interfax news agency reported.

Fighting continues “several dozens of kilometers” from the southern Russian city of Kurchatov, where the Kursk nuclear power plant is located, local official Igor Korpunkov said.

The Ukrainian invasion across the border into Kursk has now lasted for four days. Kiev said it had assembled around 1,000 soldiers for the surprise operation.

Two people were killed and 17 others injured in a Russian artillery attack on a supermarket in the eastern Ukrainian city of Kostiantynivka, the governor of the Donetsk region said.

Search and rescue operations will continue, said Vadym Vilashkin.