The indictments, unsealed during a news conference in Washington on Wednesday, represent the first time the US government has criminally charged Russian officials for cyber offences.

The officers of the FSB, Russia’s Federal Security Service and a successor to the KGB, were identified as Dmitry Dokuchaev, 33, and his superior, Igor Sushchin, 43.

Latvian-born Russian national Alexsey Belan, 29, who is on the list of most-wanted cyber criminals according to the Washington Post, and Karim Baratov, 22, who was born in Kazakhstan but has Canadian citizenship, were also named in the indictment.

Yahoo said, when it announced the then-unprecedented breach last September, that it was working with law enforcement authorities and believed the attack was state-sponsored.

The company announced a still-larger breach in December that occurred in 2013 and affected one billion accounts, though it has not linked that intrusion to the one in 2014.

with Reuters