The VA said it is working with the DOD to match data and verify those potentially affected. The VA is sending letters to those whose personal information may have been stolen, and said it has no evidence that other full-time, active duty personnel from the other military branches are affected.

In the wake of the data theft, the Vietnam Veterans of America (VVA) has joined four other national organizations and several individual veterans in a class-action lawsuit seeking judicial oversight and protection of the VA computer files.

"It is appalling to all veterans that their personal information -- information that is supposed to be held in confidence -- is potentially in the hands of individuals who can wreak identity-theft havoc," John Rowan, national president of VVA and a plaintiff in the lawsuit, said in the statement. "VA Secretary Nicholson has said he is 'mad as hell' over this incident and the breakdown in command and control of his department, and we believe him.

"However, he has yet to answer some critical questions: What was an employee of the VA doing with the names, Social Security numbers and dates of birth of all these veterans, the vast majority of whom have never availed themselves of VA services? Why is the VA collecting this information in the first place?"

The lawsuit was filed in U.S. District Court for the District of Columbia Tuesday by attorney Douglas Rosinski, of the law firm Ogletree, Deakins, Nash, Smoak & Stewart P.C. The other organizations who have joined the suit are the National Gulf War Resource Center, Radiated Veterans of America, Citizen Soldier and Veterans for Peace.