U.S. Forced to Curtail Anti-Drug Effort After Spy Plane Almost Hits 2 Airliners : Colombia: Cautious new posture in once-secret operation is a major setback in war on traffickers.

A high-priority U.S. mission to use military planes to eavesdrop on Colombian drug traffickers was severely curtailed early this month after an American spy plane was reported to have nearly collided with two Colombian airliners, The Times has learned.

The Defense Department agreed to the scale-back under pressure from the Colombian government, which had approved the politically sensitive mission on condition that it be kept secret, Administration officials said.

The cautious new posture for the until-now secret U.S. reconnaissance flights marks a major blow to a Bush Administration effort to be more aggressive in its intelligence-gathering in the region, the most important base of operations for international drug traffickers.

An earlier top-priority plan to deploy a Navy task force off the coast of Colombia also had to be abandoned after details of the proposal were reported in the press and the government of Colombia withdrew its approval of the operation.

A Pentagon spokesman on Monday disputed Colombian press accounts of the near-miss incidents, which took place March 28, saying that the EC-130 surveillance plane had never posed a hazard to either of the civilian aircraft.

But whether or not there was a near-collision, other officials said the mere sighting by the two civilian pilots of the Air Force reconnaissance plane over southern Colombia forced the government there to demand that the United States be more discreet.

In addressing the latest Colombian concerns, sources said, the Pentagon has ordered reconnaissance plane pilots to avoid any route on which they might again be spotted over Colombia. The sources refused to describe the new flight plans in detail, but one official said it is possible that the pilots might now have to stay clear of Colombian airspace altogether.

“We have now essentially decided to err on the side of safety,” the official said. “We’re keeping everybody away from everything.”

Among the classified operations believed to be affected by the new guidelines are efforts by Oklahoma-based Air Force AWACS radar planes to monitor suspicious air traffic over Colombia and attempts by the Panama-based EC-130 electronic surveillance planes to listen in on communications among drug traffickers.

These missions have proved helpful both in gathering general information about the extent of trafficking and in collecting tactical intelligence, including some information that has been beneficial to an all-out Colombian manhunt for notorious cocaine kingpin Pablo Escobar.

Administration officials acknowledged Monday that the new stand-back orders for the surveillance flights would inevitably constrain such intelligence-gathering missions. But they said the need to preserve the good will of the Colombian government had left the Pentagon with no alternative but to accept the limitations.

“There will be a limit on what we can do,” said one source who was briefed on the situation, “but the bottom line in the long run is that we have to work with the Colombians.”

The sources said U.S. intelligence agencies hope to employ unspecified “other methods” to fill the void left by the scaled-back surveillance flights. But they said that even under the most optimistic assumptions it is likely that the United States “may not be able to get the same amount of information.”

Despite the setback, U.S. officials said Monday that they remain confident of Colombia’s commitment to the anti-drug effort.

“We just have to understand that they are going to be sensitive about anything that appears to threaten their sovereignty,” one official said.

The alleged near-collisions involving the American spy plane became public in Colombia March 29 when the pilot of a SAM airliner was quoted by newspapers as saying that the military aircraft passed within several hundred feet of him over southern Colombia.

Asked about the incident by a Colombian reporter, the Defense Department confirmed that a Panama-based “Air Force C-130” flying at an altitude of 18,500 feet had in fact been in the area where the near-collision was said to have taken place.

But in its statement, reaffirmed by a Pentagon spokesman Monday, the military declared that the American plane had been flown properly.

“There was no near collision and no hazard whatsoever,” the Pentagon said, noting that the aircraft had been in contact with air controllers.

Knowledgeable sources said Monday that the “C-130” was in fact an EC-130, a variation of the basic cargo plane that is equipped with electronic surveillance equipment. They said the plane was based at Howard Air Base, just outside Panama City.

Administration officials said they believe the American pilot erred in allowing his spy plane to be spotted by the Colombian pilots.

But they said they believe that allegations of the near-collisions may have been orchestrated by Colombians sympathetic to the drug traffickers.