If your computer can’t be connected to the Internet, then you can not use the Rhino account Cloud Zoo.
You can use stand-alone licensing on a single computer or your IT staff can setup floating licenses using the Zoo over the LAN.
This should help:
https://www.rhino3d.com/6/new/licensing-and-administration
There are no other licensing options. We don’t have anything specific for defense contractors, just the three we keep describing.