@Olivier5,
That really made me wonder (for the USA, I mean). Virtually every member of the armed forces has training in using a firearm and knowledge of the principles of weapons safety, and many have practical experience in combat. (I'm quite sure, I still could assemble a pistol blindfolded as often we had to do it)
However, that has changed:
Commanders, O-5 and above, "may grant permission to DoD personnel requesting to carry a privately owned firearm (concealed or open carry) on DoD property for a personal protection purpose not related to performance of an official duty or status," the document states. (2016, Nov. 18 Defense Department directive)
http://www.esd.whs.mil/DD/