THE arrest of US Army veteran Timothy McVeigh in the Oklahoma City bombing has stirred discomfort within the military over the possible involvement of personnel with groups that espouse racial and religious hatred and political violence.
The issue is disturbing to defense officials for several reasons. For one, it seems to undermine the military's success in promoting racial integration. It is also of concern because of the lethal skills that military service imparts and the access it affords to weapons and explosives.
''I think we are all uncomfortable about the prospect that we have some soldiers, sailors, and marines who have some affiliation with these militia units,'' says a senior military officer. ''We may have a zany or two out there.''
Officially, the Pentagon insists there is no evidence that any active military personnel are supporting groups that espouse racial or religious hatreds, the overthrow of the federal government or other extremist views. Even the hint of such a possibility brings terse responses.
''Members of the active-duty military forces are not permitted to belong, to participate in organizations which are extremist or which are violence prone,'' Defense Secretary William Perry told reporters on Tuesday.
Even so, Mr. Perry has asked the armed forces chiefs to remind service members of rules barring them from ''active participation'' in extremist groups. Such participation is defined as demonstrating, fund-raising, recruiting, or training.
The regulations, however, allow ''passive activities'' associated with extremist groups ''such as mere membership, receiving literature through the mail, or presence at an event.'' The rules note that such activities are strongly discouraged.
Officials in Perry's office are examining and possibly updating a classified list of groups that in the past have ''demonstrated intent against'' Defense Department targets, says Pentagon spokesman Kenneth Bacon.
Perry's actions should not be read as an admission of military and right-wing militia ties, Mr. Bacon says. But Perry's decisions underscore the unease within the Pentagon over the possibility of links between active military personnel or National Guard members and the militias with which Mr. McVeigh has reportedly been associated. Militias and white-supremacist organizations often claim active-military personnel among their members.
MCVEIGH is the only suspect charged in last week's bombing of the federal building in Oklahoma City. But the investigation of the former Army sergeant and GulfWar veteran led the Federal Bureau of Investigation to one of McVeigh's service buddies, Terry Nichols. The two enlisted on the same day in 1988 and served in the same company of the 1st Infantry Division at Fort Riley, Kan.
Mr. Nichols and his brother, James, reportedly share McVeigh's political views, including an antipathy for the federal government, opposition to gun control and a belief that the United States is to be taken over by the United Nations.
The Nicholses were charged on Tuesday with conspiring with McVeigh to manufacture explosive devices on their Michigan farm. They have not been charged in the Oklahoma City attack.
Military officials acknowledge that it is extremely difficult to investigate personnel for involvement in extremist groups because of the constitutional protection of freedom of association. ''To my knowledge, at some point our folks may have looked into this stuff. But, basically we are still looking at freedom of association,'' says Lt. Col. Bill Hartley, an Army spokesman.
Pentagon officials say the last known discharge of military personnel for involvement with hate groups occurred in 1986, when three Marines in North Carolina were cashiered. The trio was linked to the White Patriots Party, a white-supremacist group founded by a former sergeant who was dismissed from the Army in 1979 for distributing racist literature.
The senior military officer, speaking on condition of anonymity, says he has little doubt that some current personnel are involved with extremist groups, but that the number is tiny.
''My instinct is that it is very small and very limited,'' the officer says. ''But, I would not be surprised if we had some activity among our very young servicemen, probably out of ignorance. We have a wide assortment of people that enter the military and some young guys are more easily led astray than others.''
The officer adds that the chances of involvement of service members in hate groups has diminished as the quality of officers and enlisted personnel has increased with the end of conscription. Most officers have college degrees and some 90 percent of enlisted personnel are high-school graduates.