I have not been with the VA long enough to see anyone getting fired. In private sectors, when people reach above a certain level, they don't get fired. Even in at-will states, they are usually "given an opportunity to resign." I have seen some very good people given opportunities to resign after pissing off the wrong person or messing up with their budget. In a cooperate owned and operated facility, a good colleague of mine was walked out of the building by the VP after being told to sign a pre-drafted resignation letter. He was a dedicated department head with good performance review. The only wrong move he made was sending an email about a matter that required the VP's attention, and he capitalized THANK YOU at the end of email followed by !!!. It was perceived by the VP that as if the department head was yelling at him and being rude. Prior to that, they did not have a positive relationship to begin with.
In the VA system, I am guessing they can find ways to make people transfer or resign since firing process is so time and energy consuming.