Documenting a growing gap in attitudes between prominent U.S. civilians and the nation's increasingly conservative military elite, a major new study warns that mounting distrust in civil-military relations is undermining a long history of cooperation and threatening military effectiveness.

Concern about the distancing of the military from the rest of society has reached the top levels of the Pentagon, with Defense Secretary William S. Cohen launching a campaign this year to "reconnect" America to the military and boost public understanding of the armed forces.

In the broadest and most systematic examination of the problem ever undertaken, a group of researchers backed by three North Carolina universities found the civilian-military split especially pronounced over politics.

"Over the past quarter-century, elite military officers have largely abandoned political neutrality and have become partisan Republicans," the study concluded, noting that 64 percent now identify with the GOP. "The long tradition of an apolitical military has given way to a new reality in which the elite military is probably the most solidly Republican professional group in American society."

This partisan gap is matched by an ideological divide, the study said. Military officers, for instance, are far more likely to identify themselves as conservative than are civilians, 66 percent versus 42 percent.

While stopping short of declaring a crisis, the study argued that the widening split in views and values is being aggravated by a declining number of military veterans in influential civilian jobs since the advent of an all-volunteer military 25 years ago and the passing of the World War II and Korean War generations. These trends are likely to have profound implications on the future willingness of the United States to send troops into combat, among other public policy considerations, the study said.

They already have taken a toll on the traditional principle of civilian control over the military.

"During the 1990s, the principle of civilian control has been subjected to more ongoing strain than at any time in American history," the study said.

Two dozen scholars participated in the study, which was run by the Triangle Institute for Security Studies, a research group in Durham, N.C. Results were taken from about 4,900 interviews conducted in late 1998 and early 1999. The military officers polled were those considered on a fast track to top jobs; the civilians were selected randomly from Who's Who and other reference works.

The findings have produced more than 20 academic papers on various aspects of civil-military relations. A summary report was released yesterday.

"Our research identified numerous schisms and trends that have undermined civil-military cooperation and, in certain circumstances, could degrade military effectiveness," the report said.

For most of this century, the report noted, there was a significant "veteran's advantage" in American politics: always a higher percentage of veterans in Congress than in the comparable age cohort in the general population. But this advantage has eroded over the past 25 years in both chambers of Congress and across both parties.

Now, military veterans are under-represented in the national political elite. The percentage of veterans in the House has sharply declined, from over 75 percent in 1971 to about 25 percent in 1999. A similar decline occurred in the Senate, although it began somewhat later and was somewhat smaller.

While civilian and military groups continue to express a degree of mutual respect, the study found these expressions "rest on an underlying alienation that may in time erode the surface support each claims for the other."

Military officers tend to take a negative view of civilian society, viewing it in a moral crisis, according to the report. They believe civilian society would be better off if it adopted more of the military's values and behaviors.

Civilians agree there's a moral crisis but strongly oppose the notion that military values are the answer. Moreover, despite voicing a large measure of confidence in the military as an institution, many civilians also regard the military as a self-interested bureaucracy, inclined to avoid carrying out civilian orders it does not like.

"Each harbors strong negative stereotypes about the other beneath a surface expression of respect and confidence," the study said.

Among the more intriguing arguments put forward in the study is that with fewer veterans in national political life, the United States will be more--not less--likely to get involved in military operations abroad. Reviewing all U.S. military actions since 1816, researchers found what they concluded was a distinct correlation: The more veterans in the national political elite, the less likely the United States was to initiate the use of force.

"Our results suggest that if the percentage of veterans serving in policy-making positions declines over time, other things being equal, the United States would be more likely to initiate the use of force overseas," the summary report said.

Another finding--this one about the willingness to tolerate casualties--challenged the conventional military argument that civilians are more averse to suffering battlefield deaths. Researchers found that older, more senior officers tend to be the most reluctant about taking casualties.

"The reason appears to have something to do with the zero-defect culture," said Peter Feaver, a Duke University professor involved in the project. "Casualties have become a sign of failure, and failure is something that senior officers don't want to have happen on their watch."