LONDON — For years, Russia has tormented neighboring countries with targeted cyberattacks, including blackouts in Ukraine and broad online assaults on Estonian institutions.
The United States has rarely publicly attributed blame, though experts found the fingerprints of the Kremlin on those intrusions abroad.
In a break from past practice, the State Department said publicly on Thursday that Russia had been behind a sweeping cyberattack last fall in the former Soviet republic of Georgia. It affected more than 2,000 government and privately run websites, disrupted government operations, and interrupted television broadcasts, including that of the national television station.
Secretary of State Mike Pompeo specifically attributed the attack to the Russian military intelligence agency known as the G.R.U. and its Main Center for Special Technology. The State Department linked the Russian military unit to a notorious Russian hacker group known as Sandworm, which is believed to be responsible for some of the most brazen cyberattacks around the world over the past decade.
Mr. Pompeo said in a statement: “This action contradicts Russia’s attempts to claim it is a responsible actor in cyberspace and demonstrates a continuing pattern of reckless Russian G.R.U. cyberoperations against a number of countries. These operations aim to sow division, create insecurity, and undermine democratic institutions.”
Mr. Pompeo pledged to support Georgia and other nations threatened by cyberaggression from Russia. “The United States calls on Russia to cease this behavior in Georgia and elsewhere,” he added. “The stability of cyberspace depends on the responsible behavior of nations.”
The United States was joined by Australia and Britain in blaming Russia and condemning the “reckless” attack.
The October cyberattack on Georgia, where Russia engaged in a deadly five-day conflict a decade ago over separatist regions, was a broad assault. For example, the image of former President Mikheil Saakashvili was pasted to the home pages of many sites, with the caption, “I’ll be back.”
Mr. Saakashvili was in power in Georgia from 2004 to 2013, having served two terms as president. He gave up his Georgian citizenship in 2015 and is wanted in the country on criminal charges, which he says are politically motivated.
Vladimer Konstantinidi, a spokesman for Georgia’s foreign ministry, told reporters at a news briefing on Thursday, “The investigation conducted by the Georgian authorities, together with information gathered through cooperation with partners, concluded that this cyberattack was planned and carried out by the main division of the General Staff of the Armed Forces of the Russian Federation.”
Russia’s Foreign Ministry denied that Moscow was behind the assault, with the news site RIA quoting Deputy Foreign Minister Andrey Rudenko as saying, “Russia did not plan and is not planning to interfere in Georgia’s internal affairs in any way.”