The hack targeted the email accounts of Russian and USA officials, Russian journalists, and employees of financial services and other businesses, officials said.
The Yahoo breach, McCord said, "also targeted Russian journalists; numerous employees of other providers whose networks the conspirators sought to exploit; and employees of financial services and other commercial entities".
"I believe (U.S. President) Donald Trump is using this to make it appear as if he is going after Russian hackers", he said.
Companies are more likely to be blamed for security incompetence when their networks are compromised by thieves or wayward teenagers than when they become the targets of sophisticated espionage carried out by foreign governments.
The 33-year-old Dokuchaev was reported to have been arrested in Moscow earlier this year on treason charges. Hailed as a breakthrough at the time, the five remain beyond the reach of US prosecution.
Dokuchaev, whose hacker alias was "Forb", presents a mysterious case.
The U.S. intelligence community released a report January 6 that said those hacks had been conducted with the knowledge of the Kremlin and with the intent of swaying the campaign in favor of Donald Trump.
Milan Patel, a former Federal Bureau of Investigation cyber agent and now managing director for cyber defense at K2 Intelligence, said the intermingling of espionage and cyber crime in Russian Federation had led the United States and its allies to be far more wary about alerting Moscow to criminal hackers.
Also indicted was Dokuchaev's superior, Igor Sushchin, 43. He also reaffirmed Russia's denial of any official involvement in hacking.
Dokuchaev, who worked in the FSB's information-security division, was detained in December by Russian law enforcement, on suspicion of having links to USA intelligence agencies, and may face as many as 20 years in prison if convicted on treason charges, Ivan Pavlov, a lawyer involved in case, said at the time.
The FSB hasn't commented, and the Justice Department did not confirm that.
The U.S. Government claims the four defendants breach of these Yahoo accounts allowed them to access users other accounts such as Gmail.
Injustice 2 Gets Firestorm Trailer, Introduces Source Crystals
These upgrades do not fall into the Gear category, though, and players won't be able to pay to increase character stats. The announcement stresses that the Source Crystals can not be used in order to gain advantage in the game.
Did "Weak Link" Baratov Help Unravel Case?
Russian Federation has always been known for its dynamic cybercriminal underworld, which is fueled by high technical standards and the opportunity for significant financial rewards.
The charges could change that calculation on the part of the hackers, and the intelligence services. At the same time, the government sanctioned two Russian criminal hackers with no apparent connection to the Kremlin's interference campaign. He is being held in custody, and Virk said he could not say where, or by whom. US officials also charged two other men, a Russian national and a Canadian/Kazakh national, for participating in the major Yahoo security breaches.
Rivalries between these groups mean they are constantly vying for the Kremlin's favor. They say the arrangement offers deniability to Moscow and freedom from legal troubles for the hackers.
"The United States will vigorously investigate and prosecute the people behind such attacks to the fullest extent of the law", U.S. Attorney General Jeff Sessions said.
That has largely worked, analysts say.
Russian programmer Dmitry Artimovich, who was convicted in 2013 of hacking offenses, said the FSB had made repeated attempts to recruit him.
"It's a very high profile global investigation touching hundreds of millions of people, and so we're particularly pleased to have played an important role in locating and arresting one of the people". "But you do not have to go it alone".
Since being released, Artimovich said he has been asked dozens of times to carry out hacking operations, offers he said are created to tempt him to break the law and become vulnerable to FSB pressure.
The specific individuals targeted included diplomats, executives and an investigative reporter. Last year, Russians were accused of stealing emails from the Democratic National Committee. Some of the accounts led Baratov to identify users who also had Google mail accounts, which he hacked.
The case further blurs the lines between the Russian government and cybercriminals.
The compromised accounts may have affected more than just email. After announcing the indictments USA will put out another official request for their extradition, he said. "He is clearly not a programmer", Gostev said.