‘Be afraid and wait for the worst’: What to know about the Ukraine cyberattack

After talks between Russia and Western countries over a Russian troop buildup on the Ukrainian border failed to bring results this week, dozens of Ukraine government sites were struck by hackers Friday, the Associated Press reports.

Text on some of the sites told Ukrainians to “be afraid and wait for the worst” and claimed that personal information has been leaked, but officials claimed there was no actual breach of personal data.

Ukraine has suggested that Russia was involved in the hack amid the tensions, but there’s been no firm evidence so far about who’s responsible. A 2015 hack on the Ukraine power grid that caused outages for hundreds of thousands is widely believed to be attributed to Russia, and Russian hackers have been accused of involvement in numerous other digital attacks around the world, with U.S. officials warning of the possibility of Russian attacks earlier this week. Russian forces reportedly interfered with internet and cellphone connections after the 2014 invasion of Crimea.

The Russian troop buildup has raised fears that Russia will attempt to seize more territory from Ukraine.

NATO Secretary General Jens Stoltenberg condemned the cyberattack in a Friday statement saying the alliance would work with Ukraine to bolster its cyber defenses.

“In the coming days, NATO and Ukraine will sign an agreement on enhanced cyber cooperation, including Ukrainian access to NATO’s malware information-sharing platform,” he said. “NATO’s strong political and practical support for Ukraine will continue.”

The affected sites were built by a Ukrainian software firm called Kitsoft, CNN reported, citing information from Cisco’s Talos cybersecurity unit.

Digital attacks have increasingly become a part of modern warfare and rivalry between nations.