Russians suspected in Pentagon email hack

Following warnings from top military officials about the growing threat of cyberattacks on Defense Department networks, it was revealed Thursday that Pentagon was forced to take its Joint Staff unclassified email system offline last month after it was accessed by alleged Russian hackers.

The system has been shut down since roughly July 24, according to U.S. officials, who told NBC News on Thursday that a “sophisticated cyberattack” by the hackers affected roughly 4,000 military and civilian personnel who work for the Joint Chiefs of Staff.

While it was not clear whether the attack was sanctioned by the Russian government or was the work of individuals, NBC cited the unnamed officials as saying the suspected hackers coordinated the cyber attack via social media accounts.

The officials also said no classified information was seized or compromised and that only unclassified accounts and emails were hacked — and that the system is expected to be back online before the end of this week.

The development comes months after U.S. officials revealed a separate intrusion by Russian hackers.

In April, Defense Secretary Ashton Carter said the earlier incident, which also involved an unclassified U.S. military network, exposed the growing cyber threat — as well as the improving U.S. ability to respond.

“Adversaries should know that our preference for deterrence and our defensive posture don’t diminish our willingness to use cyber options if necessary,” Mr. Carter said in prepared remarks during an April address at Stanford University, according to Reuters.