Russian hackers launched a "sophisticated cyberattack" against the unclassified email system of the Pentagon's Joint Staff, NBC News reported, citing unnamed sources.
The "sophisticated cyberintrusion" occurred around July 25 and affected as many as 4,000 military and military and civilian work for the Joint Chiefs of Staff, according to NBC.
Sources said they believe the attack involved automated equipment to gather massive amounts of information to send to multiple encrypted social media accounts whose users may have been behind it.
According to NBC, it's not clear whether the attack was sanctioned by the Russian government itself.
No classified information was hacked, according to NBC.
CBS News reported that the email system remained offline for more than a week after the intrusion.
The Pentagon did not immediately respond to a request for comment from TheBlaze.
The reports come just two months after the U.S. government announced that the Office of Personnel Management, the human resources arm of the federal government, was hacked back in May.
That alleged cyberattack, which the Wall Street Journal reported was carried out by hackers in China, may have compromised identifying information belonging to as many 4 million federal workers at every federal agency.
The FBI said at the time that it was investigating.
(H/T: NBC News)
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