The easiest and most obvious manner in which to ensure soldier safety on military installations is to allow soldiers the same rights as every other American citizen to carry firearms  on their person. People don't generally include military bases on their lists of "gun free zones" but I think that this example is the most important. It makes arguments of fear based on "untrained citizens wielding dangerous weapons" moot.

Also, the military's process for personnel selection generally (read loosely) prohibits anyone with a criminal past from enlisting or commissioning in the armed services. Any suggestions of questionable mental health of soldiers returning from war are an entirely separate matter that should have a more specific examination into the rights of gun ownership, if any such rights are deservedly infringed upon. Personally, I don't see why anyone in the military that people are afraid to let carry firearms are in the military at all. It should be a given that the people allowed to carry firearms are understood to be competent and sane.

This incident just underscores the insanity of gun control. It demonstrates that even a highly secured military installation can be easily compromised with next to no effort, and attacked with conventional weapons. When people (even soldiers) are disarmed, they become victims, and nothing more.