The U.S. State Department is implementing improvements to its computer systems, including shutting down some sections temporarily, to enhance security following a cyberattack.

Reuters quotes Jen Psaki, a spokeswoman for the department, saying the agency was upgrading “the security of its main unclassified network during a short, planned outage of some Internet-linked systems.”

The department was hit by a cyberattack in November, and implemented some upgrades at that time. Both the November upgrade and the latest one have reportedly left some department employees without the ability to send emails outside the system or to access the Internet.

The upgrade is to the department’s unclassified computer network, Reuters reports.

“In a brief statement, Psaki said the department continued to monitor ‘activity of concern’ on its unclassified network but did not address whether there had been a recent, new attack that prompted the latest security upgrade,” the story reports.

The article quotes Psaki saying in the statement: “There has been no compromise of any of the Department’s classified systems, nor of our core financial, consular, and human resource systems.”