WASHINGTON - Russian military intelligence was behind the recent spate of distributed denial of service (DDoS) attacks that briefly knocked Ukrainian banking and government websites offline, a senior U.S. official said Friday.

Deputy National Security Advisor Anne Neuberger told journalists at the White House that Washington was seeking to hold Russia to account for its aggressive moves in cyberspace.

"Russia likes to move in the shadows and counts on a long process of attribution," Neuberger said. "In light of that, we're moving quickly to attribute the DDoS attacks. We believe the Russian government is responsible for widespread attacks on Ukrainian banks this week."

Neuberger said that Americans have data showing that infrastructure connected with Russia's military agency, generally known as the GRU, "was seen transmitting high volumes of communication to Ukraine-based IP addresses and domains.”

Russia has denied any role.

  - Reuters