The US State Department has shut down its entire unclassified email system after detecting a breach in its computer network.
According to reports, the “activity of concern” was detected in the system concurrently with another cyber attack which hit the network at the White House computer network.
"The State Department, like any other large organization that has a global span, is a constant target of cyberattacks," spokesman Jeff Rathke said Monday.
He said the department, after detecting "activity of concern several weeks ago," developed a response with cybersecurity experts from the Department of Homeland Security and other agencies and is "implementing carefully planned improvements to the security of our main unclassified network."
He added he had no information to share on the source of the attack, which remains under investigation.
The breach comes weeks after the White House announced several of its unclassified computer systems were hacked.