The war against Yugoslavia is over. Now comes the battle inside the Pentagon.

With budget shares and weapon programs at stake, the Air Force is squaring off against the Army over the lessons to be drawn from the Kosovo conflict. Did it presage a lasting change in how U.S. forces will fight? Or was it an air power anomaly?

The Air Force, newly energized by the success of its stealthy warplanes and precision weapons, hopes to translate its performance into more money for radar-evading fighter jets, precision-guided bombs and reconnaissance drones.

The Army, which fumbled the deployment of AH-64 Apache helicopters to Albania and was kept out of the fight, remains determined to assert its relevance and hold on to its heavy armor and all 10 of its divisions. At the same time, Army officials acknowledge that they need to speed development of smaller, lighter units that can be deployed more quickly.

For now, the services are marshaling arguments to turn the lessons of the war to their advantage in after-action reviews, upcoming congressional testimony and budget battles due to heat up in the fall.

"It's already started, the elbowing of each other in the building," a senior defense official said. "They're using the Kosovo conflict as a jumping-off point for making their cases."

In several key respects, the operation against Yugoslavia was different from the kind of all-out, regional war against an adversary like Iraq or North Korea that the U.S. military has prepared for since the demise of the Soviet Union nearly a decade ago.

It was a limited conflict, relying largely on NATO air power. It was motivated not by a direct threat to U.S. national interests but by humanitarian concerns for ethnic Albanians in Kosovo and a desire to sustain NATO's credibility. And it was the first attempt at coalition warfare by a NATO alliance that acts on the basis of consensus and, in this instance at least, imposed extraordinary demands on commanders to minimize casualties among pilots and innocent civilians.

If this sort of measured war is the wave of the future, Air Force advocates contend air power is likely to play a more dominant role. Using B-2 bombers, satellite-guided munitions, Predator surveillance aircraft and other advanced weaponry, the Air Force was able to hit more targets more precisely and with fewer planes than ever before -- and suffer no combat casualties.

In the Air Force's view, the Kosovo conflict demonstrated for the first time that a gradual application of air power -- without benefit of closely coordinated ground forces -- can defeat a foreign dictator. Which is not to say the Air Force is ready to disband the Army or do away with traditional notions of applying overwhelming force. Even the most staunch air power advocates still believe that airstrikes work best when delivered massively from the start and when ground troops can help spot targets and drive enemy forces into the open.

But Air Force strategists say the Yugoslav experience should trigger a rethinking of conventional military doctrine.

"The whole policy of gradual escalation is back," said retired Air Force Col. Phil Meilinger, a leading expert on air power who teaches at the Naval War College and initially was a vocal critic of the NATO campaign. "Something very different happened in this war, and to simply pass it off as being an aberration is dangerous. I think we need to think through it."

Senior Army officials, on the other hand, are reluctant to view the Kosovo operation as a model for future wars or a turning point in the use of force. They say the United States still needs to be ready to fight a wide range of enemies on varied terrain -- from Middle Eastern deserts to the Korean peninsula -- and so must maintain a large land army with heavy armored units as well as lighter infantry divisions.

"We must be a full-spectrum force," said Gen. Dennis Reimer, who stepped down yesterday as the Army's chief of staff. "We cannot automatically redesign the Army in response to some specific area, whether it's Kosovo or some other place, with every crisis that crops up."

Army officials also are quick to point out that while the NATO operation eventually forced Yugoslav President Slobodan Milosevic to yield, it was not without significant shortcomings.

The airstrikes, for instance, failed to stop the slaughter and expulsion of ethnic Albanians. And in the early weeks of the campaign, alliance warplanes were easily foiled by bad weather.

Yugoslav troops, once entrenched in Kosovo, were able to hide tanks and artillery from high-flying aircraft. At times, they mixed civilians with military convoys, prompting NATO planes to hold their fire for fear of causing civilian casualties.

The air campaign only began to decimate Yugoslav forces in late May, about two months into the fight, when Kosovo Liberation Army rebels attempted to open a second corridor from Albania into southwestern Kosovo. By drawing Yugoslav armor and artillery out of hiding, the rebels provided easier targets for A-10 "Warthog" planes and B-52 bombers. In the final two weeks of the war, NATO warplanes struck twice as many tanks, four times as many armored personnel carriers and 10 times as many artillery pieces in Kosovo as they had during the previous eight weeks, according to the Pentagon.

"What you had, in effect, was the KLA acting as a surrogate ground force," said one Army general. "It was a confirmation, of sorts, of our joint doctrine, which calls for using air and ground forces together."

Although the U.S. Army would prefer to think of NATO's air campaign as a special case, many defense specialists see the conflict as underscoring the fading prospect of large land wars and the growing likelihood of smaller conflicts in remote locations -- with growing political emphasis on taking no U.S. military casualties. This does not bode well for the Army's cumbersome armored divisions.

Army leaders say they are taking steps to create a more agile, rapidly deployable and high-tech force.

They have begun slimming down Army divisions -- the service's basic organizational building blocks -- from about 18,000 soldiers to 15,700. They are experimenting with a "strike force" concept that would quickly assemble infantry, armor, aviation and other elements under a single headquarters for specific missions -- much as the Apache task force sent to Albania was organized. And they are developing the Army's own unmanned surveillance drones and precision-guided, unitary warheads for the long-range ATACM artillery system.

"We must restructure the Army," Reimer acknowledged. "We want to make our heavy divisions more deployable and our light divisions more lethal, give them more punch."

But Reimer insisted that the pace of change cannot be rushed and must avoid disruptions to current operations. With an active-duty force already down by one-third, to 480,000 soldiers, since the Cold War, the Army contends it barely has enough troops to handle mounting peacekeeping demands -- such as the new mission in Kosovo -- and still be ready to fight major regional wars.

For the Air Force, the conflict against Yugoslavia also raised questions about whether it has sufficient resources to fight one war while remaining ready for a crisis in another part of the world, as U.S. policy requires. The 11-week operation nearly exhausted stocks of some precision weapons, strained the Pentagon's limited fleet of electronic jamming aircraft and left Air Force operations elsewhere underequipped and undermanned.

"As a result of Kosovo, I'd expect there'd be more careful scrutiny of some heavy systems that hardly ever seem to be taken to war these days, and hopefully a little more respect and appreciation for those Air Force capabilities that get there quickly, are easily integrated in coalition operations and provide only fleeting or invisible targets for enemy guns," said retired Air Force Maj. Gen. Charles Link.

Still, having watched the military services battle over strategy and budget shares before, some defense analysts, including John Hillen, remain skeptical that the Yugoslav experience will make much difference. "Historically, very little ever changes in terms of the way they split up the budget," he said.