http://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/521056_dodd_2016.pdf
It gives commanders broad authority to limit this for their installations
The Joint Base San Antonio Commander has shut down any non-duty carry of any weapons
Other around the nation have done the same
I thought we fixed this in 2016 with DoD Directive 5210.56, Arming and the Use of Force.
Purely for show. It was an attempt to claim they were doing something, while insuring that nothing substantial was really done.
It gives commanders the authority to authorize people to carry weapons for defense, but does not require them to do so.
There are a thousand reasons for commanders to refuse to grant soldiers the ability to defend themselves, and almost no incentives for them to do so.
http://gunwatch.blogspot.com.au/2016/11/dod-contingency-for-president-trump.html