Lt. Col. David Goldfein, commander of the Air Force's 555th Fighter Squadron, took off in his F-16CG from Aviano, Italy, at 7:30 a.m. Tuesday in search of Serb forces near Mount Pastrik along the Albanian-Kosovo border. For the next six hours, as the forward air controller, he guided nine groups of fighters and their escorts to Yugoslav troops battling Kosovo rebels below.

In wave after wave, French, then Canadian, then Spanish, then American warplanes threw their weapons against Yugoslav artillery, tanks and revetments. Goldfein watched the Yugoslav positions and equipment burn, as he had watched dozens of Kosovo villages burn from Serb torches over the last 2 1/2 months.

As he returned to base, Goldfein thought about how extraordinary the international air campaign looked from his cockpit. The accented English spoken by some pilots was the only distinction in the otherwise seamless air operation he flew that day.

"It was NATO at its best," Goldfein said yesterday in a telephone interview.

Goldfein and others involved in the air war were witnesses, on a daily basis, to the step-by-step development of a larger, more capable NATO strike force whose pilots learned to fly better together as their political leaders learned over 10 weeks of bombing to accept greater military risks in pursuit of victory over Yugoslavia. Like a chrysalis whose case thickens day after day, NATO's first war hardened just long enough to force compromise from President Slobodan Milosevic.

In the opening days, NATO's top commander, Gen. Wesley K. Clark, brought his target lists by helicopter from his military headquarters at Mons, Belgium, to NATO headquarters in Brussels, only to have many of them -- a Belgrade hotel and television station, Milosevic's home and downtown command center -- stricken by allies wary of public reaction at home.

But two months into the war, the atmosphere had changed. NATO allies proved unflappable after the accidental bombing of the Chinese Embassy in downtown Belgrade. Instead of demanding a halt to bombing in Belgrade, many sent their embassy addresses into the intelligence cell of Clark's Joint Operations Center in Mons, just to make sure the warplanes knew where they were.

In a meeting with the 19 ambassadors of the North Atlantic Council on May 26, Clark showed them a building in Belgrade he intended to strike, pointing out it was across the street from the embassy of a new NATO nation and down a few blocks from the embassy of a veteran member nation.

Instead of scratching it from the list, the new NATO member asked, "So I guess I should tell my people not to sleep in the embassy tonight?" according to a NATO official present at the meeting.

"That's exactly right," Clark responded. "And board up the windows."

"Can we use tape? Or should we use plywood?" asked the representative from the other nearby embassy.

"Plywood," Clark responded.

Commanders at the outset got 400 planes, three days of targets and instructions not to get any pilots or civilians killed. But almost from the beginning they pushed Washington political leaders -- who supplied two-thirds of the aircraft -- and those in European capitals to send more planes, approve a broader list of targets and allow more aggressive tactics against Yugoslav forces hiding in the woods and buildings in Kosovo.

Commanders tweaked their tactics and employed new assets to compensate for the restrictions and for their biggest military handicap, the lack of NATO ground troops.

They employed long-range bombers, the B-1 and B-52, to herd enemy forces into vulnerable positions where they could be bombed; they vastly improved the time it took for a satellite or video-snapping drones over Yugoslavia to relay images of targets through intelligence analysts in Britain and back to pilots taking off from Italy; they put the Air Force's most sophisticated planes and its most expensive missiles up against individual tanks and artillery pieces, or clusters of troops.

The vast majority of their weapons were guided to their targets by satellites, lasers or global positioning systems. Among the 700 U.S. and 300 allied aircraft involved in the war, six $2 billion-a-copy B-2 stealth bombers dropped more than a million pounds of munitions during the first half of the war alone.

Not only were the gray, batwinged planes debuting in combat but they also were flying 33-hour round trips from Whiteman Air Force Base in Missouri, extending the global reach of U.S. air power in future wars.

NATO warplanes and guerrillas of the secessionist Kosovo Liberation Army worked together to kill more troops and destroy more military equipment last week than in any other week of the war. Operation Arrow, a two-pronged offensive along the Albanian border, forced Yugoslav troops to mass in the open. NATO planes, including the nine fighter packages that Goldfein led, swooped in, killing hundreds of soldiers and destroying dozens of tanks, artillery pieces and armored personnel carriers.

Every single day in the 72-day confrontation, NATO's political and military leaders declared confidence in the air war. The truth, however, was that in the weeks leading up to its conclusion, top military and political officials in Washington and Europe had increasing doubts that a casualty-free war would work before the onset of winter.

As peace negotiators were finishing up in Belgrade Wednesday night, Air Force Gen. Joseph W. Ralston, vice chairman of the Joint Chiefs of Staff, was standing in the Willard Hotel ballroom here explaining the historical limits of air power to a small knot of reporters pressing him on whether warplanes could force Milosevic to the table.

Precision bombing could destroy troops and equipment, and it could "degrade his forces," Ralston said, but there was no guarantee it could do more. Political leaders understood this too, he said, and they were willing to keep bombing for months, if need be.