NATO's chief military commander, Gen. Wesley K. Clark, sought to rebut critics of the air offensive against Yugoslavia today by releasing a long-awaited study that said allied bombs destroyed or damaged about a third of the Yugoslav army's weapons and vehicles in Kosovo.

Clark produced a mass of evidence drawn from declassified analyses, cockpit videos, pilot debriefings and reports from ground inspection teams to demonstrate that NATO did not exaggerate its claims of having inflicted a crippling blow to Yugoslav army and Serbian police forces.

"We destroyed, we struck enough, and we succeeded in ending the conflict on NATO's terms," Clark said. "The results of this study are not so far off what we believed them to be at the end of the war."

NATO sources said Clark, who during the war angered his superiors at the Pentagon for pressing to send troops to Kosovo, if necessary, was eager to lay out his version of events before a separate Pentagon study of the air campaign is published. In July, the Clinton administration asked Clark to step down as Supreme Allied Commander three months ahead of schedule next year.

The 78-day NATO air campaign ended in June with an agreement by Yugoslav President Slobodan Milosevic to withdraw his government's forces from Kosovo, a province of Serbia, Yugoslavia's dominant republic, and to allow the deployment of tens of thousands of NATO peacekeepers there.

But Clark's conduct of the bombing campaign has been challenged by critics--including some within the Pentagon--who claim that NATO's failure to strike at military forces hard and early in the war allowed the Belgrade government to escalate its repression and expulsion of nearly 1 million of Kosovo's ethnic Albanians, more than half the population.

Clark successfully pressed NATO's 19 governments to consider the possibility that allied soldiers would have to launch an invasion if coercive bombing raids did not work. Today, he said that the conflict was brought to a close only when Milosevic realized that he faced an imminent ground invasion if he did not accept NATO's demands.

"I think he had ample evidence to conclude that, had he not conceded when he did, that the next step would have been the long-awaited and much-talked-about NATO ground effort," Clark told reporters.

The study produced by Clark showed that at least half of the 1,955 target hits reported by NATO pilots could be confirmed. Among the damaged or destroyed targets in Kosovo were 93 tanks, 153 armored personnel carriers, 339 military vehicles and 389 artillery pieces and mortars.

Clark chastised Western media outlets that accepted a claim of Gen. Nebojsa Pavkovic, the commander of the Yugoslav Third Army in Kosovo, that NATO had struck only 13 tanks, six armored personnel carriers and 27 artillery pieces. He noted that Pavkovic also declared that 47 NATO aircraft had been shot down--when in fact only two planes were hit.

Clark has met many times with Milosevic and believes he has come to know the Yugoslav leader. He said Milosevic lost the war over Kosovo by falling victim to a series of miscalculations about Western resolve.

During a meeting in Belgrade last January at which NATO presented its list of demands for ending the Kosovo crisis, Clark recalled that Milosevic rejected NATO's terms and insisted that Kosovo "was more important than his head." Having lost four wars in 10 years and seen Serbia become increasingly isolated, Clark said Milosevic is now "struggling to save his head."

Known as a scholarly maverick, Clark has never won many friends among the Pentagon brass. His insistence on pressing the ground invasion option and his decision to deploy U.S. AH-64A Apache helicopters to Albania as a possible prelude to a land invasion angered Pentagon advisers who were opposed to the idea of committing U.S. troops to a ground war in Kosovo.

In defending the way he ran the Kosovo campaign, Clark said it was an unusual and "asymmetrical" military engagement that required innovation and political sensitivity. "Strictly speaking, this was not a war," he said, noting that bombing raids were just one dimension of a coercive effort.

Clark emphasized that he does not believe that "battle damage bean-counting" is an effective measure of the campaign and that the only criterion that matters is that Milosevic finally accepted all of NATO's key conditions. "The bottom line answer to the question of how much damage NATO had inflicted was: Just enough," he said.

Despite his success, Clark is said by NATO officials to feel embittered about the way he has been treated in the aftermath of the conflict. In contrast to Gens. Norman Schwartzkopf and Colin Powell, the two U.S. commanders who led the allied effort in the Persian Gulf War against Iraq, there have been no ticker-tape parades, no special awards ceremonies and no multimillion-dollar book offers for Clark.

In late July, Clark was told by Gen. Henry Shelton, chairman of the joint chiefs of staff, that he would have to leave his post three months early to accommodate the need to move Shelton's deputy, Gen. Joseph Ralston, into the top NATO job.

Clark refused to elaborate on his plans after he leaves NATO, saying only that he has no plans to write his memoirs.