DHS wrote this little gem:

http://www.fas.org/irp/eprint/rightwing.pdf

(U) Disgruntled Military Veterans
(U//FOUO) DHS/I&A assesses that rightwing extremists will attempt to recruit and
radicalize returning veterans in order to exploit their skills and knowledge derived from
military training and combat. These skills and knowledge have the potential to boost the
capabilities of extremists—including lone wolves or small terrorist cells—to carry out
violence. The willingness of a small percentage of military personnel to join extremist
groups during the 1990s because they were disgruntled, disillusioned, or suffering from
the psychological effects of war is being replicated today.