In the war over Kosovo, the military finally obtained its holy grail: victory without a single U.S. casualty in combat. And that worries a lot of military professionals.

Whatever political pressures commanders had felt to avoid casualties, the bar has just gone up.

"What soldiers are now being told is, your first mission is no casualties," said retired Army Col. Don Snider, a political science professor at the U.S. Military Academy in West Point, N.Y. "What will this do to the ethic of self-sacrifice, when the political guidance is to accept no sacrifice?"

Efforts to avoid casualties led to remarkable results in the war against Yugoslavia. NATO's 33,000-sortie, 11-week air campaign scored a near-perfect safety record, with no pilot losses due to hostile fire and just two deaths in a helicopter crash during a training mission in Albania.

But achieving zero combat casualties required adjustments in strategy and tactics that carry significant implications for the Pentagon.

The focus on minimizing casualties played a part in the decision to hold ground troops out of the fight and rely on airstrikes. It was the reason, too, that commanders chose to keep attack planes at altitudes above 15,000 feet during the early weeks of the campaign, out of range of some Yugoslav air defenses. And it prompted the United States to commit what was, given the size of Yugoslavia, an unusually large number of intelligence-gathering and EA-6B Prowler jamming aircraft.

"If you think that future conflicts are going to be like Kosovo, where the American public isn't very engaged and the political types will be supportive only if things don't get messy, then you need a different force structure so that you never have losses and can conduct very conservative campaigns," one defense policymaker said.

While good commanders always have sought to keep casualties as low as possible, this has turned into a preoccupation in recent years, based on the presumption that public support for military action will crumble as soon as the bodies of U.S. soldiers show up on television.

"We have gotten into this mentality where we feel the American public will cut and run if we have any casualties, and therefore we have to operate in a manner that absolutely minimizes military losses," the senior policymaker said.

Many American GIs resent the implication that they are cowards unwilling to take risks. They say it is the politicians who hold back the military, not vice versa.

As evidence that Americans are increasingly reluctant to accept casualties, defense officials often cite the quick erosion in 1993 of political backing for U.S. involvement in Somalia after 18 Army paratroopers and Special Forces members were killed during a Mogadishu firefight. The deaths set off a push in Congress to withdraw American forces from the East African nation, even though the U.S. mission was far from accomplished.

Sensitivity to casualties may be increasing partly because the Pentagon has been so successful in avoiding them. In the 1991 Persian Gulf War, 148 soldiers were killed by hostile fire, out of about 700,000 American troops sent to the region. Only four U.S. soldiers died in the 1994 Haiti intervention, three of them by suicide.

Additionally, officials say, public expectations of bloodless battle have been heightened by images of precision-guided munitions fired from ships and planes over the horizon from their intended targets. Then, too, the end of the Cold War removed the threat of a superpower confrontation, either with nuclear missiles or with massive tank battles in Europe, that had caused generations of Americans to expect heavy casualties as a consequence of conflict.

Some defense experts worry that U.S. sensitivity to combat deaths creates a kind of Achilles' heel for American armed forces, encouraging adversaries to think they will win if they can only land a few blows. This may be one reason why Iraqi President Saddam Hussein persists in trying to shoot down American warplanes, even as his air defenses are methodically demolished in retaliatory U.S. strikes. Or why Yugoslav President Slobodan Milosevic figured he might be able to beat a NATO force far greater than his own.

In Europe, the British and French appear less preoccupied with casualties and more inclined to regard soldiers as professionals for whom risks are part of the job. During the Yugoslav operation, Europeans spoke critically of what they saw as a hypocritical gap between U.S. rhetoric portraying Milosevic as a modern-day Hitler and American reluctance to commit ground troops.

The dichotomy was not lost on some in Washington, either.

"I wondered as this went on whether there was a calculus being made here, that while it was important to be involved, our national interest was judged not so great as to justify the wider risk of casualties that would have come with a ground war," said Sen. Joseph I. Lieberman (D-Conn.), a member of the Armed Services Committee who had urged NATO to prepare for a land invasion of Kosovo.

Despite the Pentagon's recent string of low-casualty conflicts, military commanders warn against expecting that all wars will turn out as sparing of U.S. forces as the last one.

"There are some things that you're going to have to fight for and put forces on the ground for, and there are going to be casualties and we've got to accept that," said one four-star general. "To think that it's going to be a push-button war, and we can do everything from 15,000 feet, really is somewhat idealistic."

Limiting Casualties

The U.S. managed to avoid casualties in Kosovo. Below are casualty comparisons with past conflicts.

Conflict

When

U.S. casualties

Iraq

1/91 to 9/91

148 in hostilities

235 not by hostile fire

Somalia

12/92 to 3/9

429 in hostilities

14 not by hostile fire

Haiti

9/94 to 4/9

64 not by hostile fire

Kosovo

March to June

None in hostilities; two in training accident