Given the crowd that seems to cluster around HN, I'm pretty sure that you're very unlikely to get a solid understanding of what USian defense contractors are doing these days.

A great many of today's Silly Valley inhabitants are significantly anti-DoD, and the subset of the folks that take the time to comment on HN seem to come nearly exclusively from the anti-DoD set. (Why would anyone who _does_ defense work and thinks that it's virtuous talk about it openly here, when they're likely to just get screamed at for being a civilian-killer and flagged into oblivion?)

If I were you, and were looking for answers, I'd try to start talking to recruiters for the various defense contractors and also start hitting up folks doing work in your area of interest to get an idea of what's going on, and who's doing good work in the space.

well on top of my head it's boeing, lockheed, raytheon for private; cia, nsa for public (govt).

you may google current openings they may have, and during screening interviews you may inform them about your experience and skills and they may inform you if there's any fitting role for you.

it's also tough to answer which one is the best because the info you need to answer that question is rarely publicly available.