The White Supremacist gunman who killed a guard at the Holocaust museum blocks from the White House was discovered to be an army veteran. His service though was in WW2 so does that count? Come on, that was the good war!)
A Christian Science Monitor report "With the Holocaust Museum shooting, the Army is eyeing recruits more closely for extremist and gang ties " assures us that the military is keeping a closer check on who joins now, though earlier in the decade they were allowing wavers for criminals of all kinds and other indications that recruits were members of gangs or white supremacist 'societies'.
And, in fact, two reports in the last dozen years have looked at ways to keep violent types out of the military. Yeah, that does seem weird, but those who do not believe in the rule of law violent types really shouldn't be allowed to control the outcome of other service member's lives, have access to military equipment, or be trusted in the proper conduct of even necessary war.
They say there is Aryan Nation graffiti in Baghdad put there by some of our troops. That makes you wonder if some of the atrocities committed in Iraq might be due to a mindset of a certain number of those recruited for the war, or maybe most of it is just due to the mindset installed in war to keep down American casualties while conquering a nation so that Chevron can lay claim to a 75% return on it's oil.
A 2006 study by the Southern Poverty Law Center was used by the government in examining the results of homegrown extremist groups using the military as a training ground (and in the early 90sas a source of free weapons). That study is both available and a good read. It even reports on weapons thefts by supremacists in the early 90s which should have created a neon sign when a 1998 study about keeping such people out of the military. This study is not available, but an abstract and chance to buy the report is at Storming Media "Gangs, Extremists Groups, and the Military: Screening for Service "
The point made above is that the Bush administration didn't need to wait until the 2006 report came out, but had the evidence to know they shouldn't have opened the services to people who were likely to use their military training to skirt or attempt to destroy the rule of law in the US.
Also, though, it is rather funny that these types get into the military at all given that an openly gay person can't serve, and he or she is much less likely to ever have been a dangerous criminal.
The SPLC study shows that many commanders do know of supremacists in their midst and do little to nothing about them, making a reek of hypocrisy rise from the officers in question.