The government already does this for some things. SIPRnet is for the transmission of information classified up to secret and is airgapped from the public intern

The government already does this for some things. SIPRnet is for the transmission of information classified up to secret and is airgapped from the public internet. This is where the Bradley Manning leaks came from. JWICS and NSANet are run along the same lines, but they transmit information classified up to Top Secret/SCI.