How can the military best reduce active shooter threats (like Fort Hood)?

This is a much more difficult question than carrying a weapon.  It is indeed true people are capable of doing the greatest harm where others are defenseless.  Yet, we still gather in church and go to the PX. 
I'm not a gun-nut, nor am I a peace-at-any-price wimp. I am a believer in training.  And I believe in our servicemembers.

We are trained to go out an break things and kill people - if you were looking at it from a video game point of view.  The biggest problem is that we are all different in our ability to cope with stress.  What may be traumatic to one person may be like water off a duck's back to another. I'll wager good money that most of my Air Force brethren who've served with Marines in the combat zone have found them to be callous, if not down right mean when it comes to human life. The degrees of meaness and such vary - and as a MCRD survivor I truly believe it's because of training. 

Marines are taught to go into combat - the same as the Army. Only, our leaders forget we have to come home.  They forget about it during indoctrination because it probably doesn't work to create the kind of people needed to win wars.  I'm not a psychologist either - however, I am positive there is a culture difference between the military and the rest of the American population - otherwise, why would we call them civilians?

Most of you are very well aware of the resources available for PTSD, suicide prevention, sexual assaults, EEO complaints - we even have Yellow Ribbon events to welcome troops home.

Yet again - we are all different. 

I needed to be verbally abused by one of my best friends and mentors before I could admit to "having an issue" with PTSD.  I was certainly not in combat - according to the Army or the Marine Corps.  Yet, I was there too.  And like many of us, I worked until the job was done and then went and worked some more because the job was never done.

The point is that coming back was traumatic for those who came before us - and they were tough men and women (they came back too).  They did their share of bad things too - we just didn't have the 24 hour news cycle like we do now.  Coming home now is just as traumatic - we cannot go jumping into a war expecting bodybags and not expecting our men and women back who bloodied the other side far more than they bloodied us. 

A former manager of mine started crying during a meeting with me.  She said she was so upset by the video of all the children who had died in the Syrian chemical attacks.  In virtually the same breath she said she wished WE would go over there and do SOMETHING about it.

I looked at her and said, "So, you'd rather see my son dead?  He's 21 and wanting to follow in my footsteps.  And what about me?  I'm still in the National Guard."

Needless to say, she's not my manager anymore.

My friends - guns are not the problem - train me to carry a gun out in the open - give me a nice band to put on my hat or wear like a PT belt - And also make sure I have the other tools I need to solve my internal problems without turning to the weapon at my side.

Just my two cents.  

1SG Hansen, I would even go one further and say that there should be a screening every couple of years as mind states and life situations may change.

SSgt Fair, it is somewhat deterrance, but moreso the ability of one to protect themselves.