SIPRNET

The SIPRNet (Secret [formerly Secure] Internet Protocol Router Network) is a system of interconnected computer networks used by the U.S. Department of Defense and the U.S. Department of State to transmit classified information (up to and including information classified SECRET) by packet switching over the TCP/IP protocols in a "completely secure" environment. It also provides services such as hypertext documents and electronic mail. In other words, the SIPRNet is the DoD’s classified version of the civilian Internet together with its counterpart, the Top Secret and SCI Joint Worldwide Intelligence Communications System, JWICS.
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