Pentagon imposed emergency shutdown of computer network handling classified material

The Pentagon on Tuesday ordered the emergency shutdown of a classified internal communications network, three Defense Department sources confirmed.

The unprecedented daytime shutdown comes amid recent revelations that other federal agencies, including the Department of Homeland Security, were breached by hackers.

The Defense Department alerted employees that the SIPRNET system was being shut down in the late morning for emergency software updates, the sources told Just the News.

The Pentagon did not immediately return a request for comment, including one on whether the shutdown was related the hacking reported Sunday, allegedly by Russian agents.

The system, known as the Secret Internet Protocol Router Network, handles classified information, up to the secret level, and was shuttered for several hours.

"This has never happened in the middle of a work day," one Pentagon official said. "Updates usually are done on weekends and after hours late at night. This was done on an emergency basis."

The shutdown applied only to computers handling the classified material, and was not imposed on other computers or on phone systems.