If they’re living and working on a closed base 20 miles into the desert from Las Vegas (or anyplace remote and secure), it might be hard to reach them there.
Of course, if they were living off base, that might be different.
The equipment and personnel have to get there somehow and re-supply and parts, too. They also can’t do anything but the largest of UAVs from a distance. As I have said before, we built those technologies, we know how to keep them from being used against us.
Visualize the nanobot-equivalent of an aircraft carrier, something about a foot to a couple yard long. It would fly, crawl, or burrow to within range of the target, then release the nanobots, meanwhile providing them with communications-relay and maybe extra compute-power.