The US State Department was forced to temporarily shut down its unclassified email system on Sunday after being hit by hackers, as reported by the Associated Press.
This happened after a department official noticed "activity of concern" that had occurred at a similar time to a previous attack against the White House computer network.
Since the incident was revealed to the public, the US Postal Service and National Oceanic and Atmospheric Administration have also said they were targeted.
Email was shut down as a result, as well as some of the State Department's web systems, in order to improve security to the network. The official said classified systems weren't affected by the hack, however.
They told the New York Times: "This has impacted some of our unclassified email traffic and our access to public websites from our main unclassified system."
Though this most recent attack has been linked with the one on the White House earlier in the year where a database with customers' phone numbers and email addresses was accessed it is unclear whether they are actually related.
The systems have been temporarily shut down in order to make the improvements, but it is expected they will be fully restored in the near future.
