Often, no. This is serious work being carried out by adults that need to come together. There is no replacement for the water cooler yet. I made the decision to explicitly seek out in-office, on-location defense work. The seridiputous conversations and relationship building was not happening in remote work. I'm someone who has always worked from home and I still do every week but my career and life were going no where typing at people through Slack and building meaningless web apps--despite making enough money to be reticent to tell most people my earnings level.
Now I'm building software, involved intimately with designing and interfacing with specialized hardware, and travelling to interesting places doing interesting things with interesting people-- occasionally toppling off of combat machines. I took a 30% pay cut to do it. No regrets whatsoever, living life.
Most Top Secret work occurs in a SKIF. Basically you enter, lock your phone, smartwatch, and whatever else in a locker, then enter the area where the work gets done. This area is regularly swept for bugs and whatnot.
You can't work on "top secret" stuff on your own due to OpSec.
