The Pentagon shut down its Joint Staff unclassified email system two weeks ago due to " sophisticated cyberattack" by alleged Russian hackers, U.S. media said Thursday.
Quoting U.S. officials who spoke on condition of anonymity, the U.S. TV network NBC News reported that the intrusion happened around July 25 and affected about 4,000 military and civilian personnel working for the Joint Staff.
The officials said the alleged Russian hackers coordinated the cyber attack through social media accounts, adding that the U.S authorities could not decide whether the Russian government was behind the attack, the report said.
In another hacking incident last year, alleged Russian hackers breached the White House's unclassified computer system and reportedly read U.S. President Barack Obama's unclassified emails.
