The only high risk areas are where you start, and where you finish, because those are known positions. Everything else can be variable....and nobody is any the wiser, because the only thing that's really different is that the trucks have zero DOT/MC numbers on the side and they have GSA plates on the truck/trailer....and I highly doubt that they stop at Weigh stations along the way. :)

https://www.youtube.com/watch?v=EyjQb3oJi80 -- this is a video of how the military transports warheads around: I'd assume many of the same types of transports are similar in nature between the NNSA and the DOD.