Cyber operations have been a recurring aspect of the conflict in Ukraine, which began when Russia annexed Crimea in 2014.

Suspected Russian hackers cut power in parts of Ukraine in 2015 and 2016, and unleashed devastating malware known as NotPetya in 2017 that began infecting organizations in Ukraine but spread globally, causing billions of dollars in damage. The US Justice Department blamed the incidents on Russia's GRU military intelligence agency.

"Over several years, we have observed a pattern of malicious Russian behaviour in cyberspace. Last week's incidents in Ukraine bear the hallmarks of similar Russian activity we have observed before," Chichester said on Friday.

The United States is also on watch against potential cyberattacks as Russia masses troops on its border with Ukraine. Russia denies it is planning an invasion.

Russia would consider conducting a cyberattack on the United States if Moscow perceived that a US or NATO response to a potential Russian invasion of Ukraine "threatened [Russia's] long-term national security," according to a January 23 Department of Homeland Security intelligence bulletin obtained by CNN.

"Russia maintains a range of offensive cyber tools that it could employ against US networks — from low-level denials-of-service to destructive attacks targeting critical infrastructure," said the memo, which was distributed to critical infrastructure operators and state and local governments.

President Joe Biden said at a recent press conference that the United States could respond with cyber operations of its own should Russia conduct additional cyberattacks in Ukraine.