Department of Defense Directive 5210.66 is the regulation that disarms military personnel on military installations unless they’re directly involved with security. Deputy Secretary of Defense Donald J Atwood signed the document—“Carrying of Firearms by DoD Personnel”—-on March 17, 1992 during the administration of Bush the Elder. It’s remained in force ever since. Click here for the full document that disarmed United States military members and civilians on base. Here’s the relevant bit . . .
The authorization to carry firearms shall be issued only to qualified personnel when there is a reasonable expectation that life or DoD assets will be jeopardized if firearms are not carried. Evaluation of the necessity to carry a firearm shall be made considering this expectation weighed against the possible consequences of accidental or indiscriminate use of firearms.
Given the attack at Fort Hood and, now, the Washington Navy Yard, can we assume that there’s a reasonable expectation that life or DoD assets will be jeopardized if firearms are not carried?