NBC News reported Russian hackers have compromised computers at the Pentagon, an unclassified email system has been shut down in response of the attack. The attack compromised data belonging to 4,000 military and civilian personnel who work for the Joint Chiefs of Staff. The system should be back online before the end of this week. The officials did not provide further information on the attackers, it is not clear if the Russian Government backed the hackers. The nature of the cyber attack and of the chosen target suggest the involvement of a state actor as confirmed by the officials.”]
Source: http://securityaffairs.co/wordpress/39180/hacking/russian-hackers-hit-pentagon.html