Russian hackers attacked a satellite internet network in Ukraine causing thousands of modems to go offline at the beginning of the war in Ukraine, Britain and the European Union said on Tuesday.

The digital assault against Viasat’s KA-SAT network in late February took place just as Russian armour pushed into Ukraine and helped facilitate President Vladimir Putin’s invasion of the country, the Council of the EU said in a statement.

“This cyberattack had a significant impact causing indiscriminate communication outages and disruptions across several public authorities, businesses and users in Ukraine, as well as affecting several EU Member States,” the statement said.

“This unacceptable cyberattack is yet another example of Russia’s continued pattern of irresponsible behaviour in cyberspace, which also formed an integral part of its illegal and unjustified invasion of Ukraine,” it added.

The remote sabotage caused a “huge loss in communications in the very beginning of war,” Ukrainian cybersecurity official Victor Zhora said in March.

Russia routinely denies it carries out offensive cyber operations. The Kremlin did not immediately respond to a request from Reuters for comment.

Western intelligence agencies, including the U.S. National Security Agency, French government cybersecurity organisation ANSSI, and Ukrainian intelligence were investigating Russia’s potential role in the attack in the days after it, Reuters reported at the time.

A British Foreign Office statement quoted Foreign Secretary Liz Truss as saying the cyberattack was a “deliberate and malicious attack by Russia against Ukraine”.

Russia’s primary target in the attack was the Ukrainian military, but it also disrupted wind farms and internet users in central Europe, the statement said, citing Britain’s National Cyber Security Centre (NCSC).