I work for a contractor to the Federal Government on the civilian side, and am a Reservist as well. On the civilian side, I am able to vape all day long. Based on who is in attendance, I puff away at meetings, briefings, and especially mandatory training sessions.

Everyone within our company is cool with it, and it never causes a problem. It actually sometimes adds some levity to the meeting if someone goes half-cocked and says something really stupid and I feel the need to take a nice 6-second drag to keep from saying something myself! LOL!
On the Army side of it, my relationship with my Cdr and direct supervisor is really good. Once again, gauging who is in the room or building is a first. If a high-ranking officer or official is around, it's easier to just go into my office until I know whether they are closed minded to the idea, or if they actually vape themselves. Of course, rank does indeed hold some privilege, so the person that decides to complain would have to have their ducks in a row first.
So far the way that I have been accepted has been pretty good. And I have yet to meet someone who doesn't admire another person for not smelling like smoke!