The Non-classified Internet Protocol (IP) Router Network  (NIPRNet) is a private IP network used to exchange unclassified information, including information subject to controls on distribution,  among the private network's users. The NIPRNet also provides its users access to the Internet.
NIPRNet is composed of Internet Protocol routers owned by the United States Department of Defense (DOD). It was created in the 1980s and managed by the Defense Information Systems Agency (DISA) to supersede the earlier MILNET. 
Over the last decades, NIPRNet has grown faster than the U.S. Department of Defense can monitor. DoD spent $10 million in 2010 to map out the current state of the NIPRNet, in an effort to analyze its expansion, and identify unauthorized users, who are suspected to have quietly joined the network.  The NIPRNet survey, which uses IPSonar software developed by Lumeta Corporation, also looked for weakness in security caused by network configuration.  The Department of Defense has made a major effort over the last few years, to improve network security.  The Pentagon announced it was requesting $2.3 billion in the 2012 budget to bolster network security within the Defense Department and to strengthen ties with its counterparts at the Department of Homeland Security.