The massive U.S. air operation to patrol the skies over southern Iraq went into temporary retreat last fall when Iraqi fighters repeatedly darted into prohibited airspace.

More than a week of regular violations of the so-called no-fly zone over southern Iraq went unanswered by U.S. warplanes armed and readied for air-to-air combat. Interviews by The Associated Press with military commanders, combat pilots and senior Pentagon officials in recent weeks showed a reluctance in the top ranks to challenge Iraqi fighters - even though the U.S. and allied forces greatly outnumbered the intruders.Three weeks after that spate of incursions, Iraqi President Saddam Hussein touched off an international crisis by threatening to shoot down U.S. spy planes.

"Yes, we did back away," said Air Force Maj. Gen. Roger Radcliff, who commanded the operation at the time. "After a period of days, we adjusted that stance. But we never gave up the no-fly zone."

Some Air Force pilots who flew the missions in the no-fly zone in southern Iraq, where the United Nations since 1992 has barred Iraqi military flights, expressed exasperation.

"The Air Force leadership that was running the war in Southwest Asia was so conservative they never let us get in a position where we could engage," Capt. Chris Pru-sak, an F-15 pilot, told the AP.

"They were just taunting us," Prusak said of the Iraqi fighters.

Air Force Lt. Mark Reents, another F-15 pilot, said in an interview: "We were initially pushed 90 miles to the south" by his military commander to avoid a clash with Iraqis. After several days of violations, "incrementally, we were allowed to move north," he said.

Both pilots continue to fly F-15s for the Air Force's First Fighter Wing based at Langley Air Force Base, Va.

Iraq began the series of incursions into the no-fly zone last Sept. 29, sending small numbers of MiG-25 and other fighters into the prohibited area daily, usually two planes at a time. A senior defense official, who spoke on condition of anonymity, said the Iraqis would turn on ground-based radars to determine when there were few American planes in the immediate area. They would then carve shallow arcs below the 33rd parallel, which marks the northern end of the southern no-fly zone.