" The camera-equipped MDARS can scoot around pre-determined paths on its own, alerting flesh-and-blood guards when it encounters an intruder or a broken lock. In development by the Navy and General Dynamics since the early 1990s, the diesel-fueled sentry ‘bot can operate for up to 16 hours, and reach a top speed of 20 miles per hour. The U.S. military has experimented with using the MDARS machines to patrol some of its Hawthorne Army Depot in Nevada. The bots have even been tested with automatic weapons — though I doubt that’s the plan at the nuke site" - Graham Sergeant