US Department of Justice indicted two Russian FSB spies and two hackers allegedly hired by the Kremlin to steal the personal information of some 500 million Yahoo! users in 2014, media reports said.
This is the first time that the US government has presented charges regarding cyber-attacks against Russian officials.
At a press conference at the Justice Department on Wednesday, acting Assistant Attorney General Mary McCord said that the accused stole Yahoo! data to spy on Russian reporters, employees with the financial services and officials of both the US and Russian governments, Efe news reported.
McCord said that the accused also attacked the Yahoo accounts of personnel working in cyber-security, along with diplomatic and military personnel.
The Yahoo! data also helped the accused access the internet accounts of the victims on other platforms, including Google, because the victims used the same passwords for multiple accounts.
The Russian Federal Security Service (FSB) agents accused are Dmitry Dokuchaev and Igor Sushchin, two officials who were tasked with investigating cyber-crimes, McCord said.
The 2 others are Alexsey Belan, one of the hackers most wanted by the FBI, and Karim Baratov, who was arrested on Tuesday in Canada.
The news about the cyber-attacks came after Yahoo! agreed in July 2016 to be bought by the communications giant Verizon, an operating totalling $4.8 billion that was called into doubt because of the attacks.