Obama continues to push only mental illness solutions at Fort Hood memorial

Obama's talk at the April 9th memorial at Fort Hood again emphasized only mental illness.

In our open society, in advanced bases like this, we can never eliminate every risk, but as a nation, we can do more to help counsel those with mental health issues, to keep firearms out of the hands of those who are having such deep difficulties. As a military, we must continue to do everything in our power to secure our facilities and spare others this pain. . . .

The question is: what happens if you can't accurately identify all the threats due to mental illness?  What happens if the threat is something other than mental illness?