WASHINGTON -- The Cold War strongly guided official America's early attitude toward close encounters with flying saucers, whatever they were, says a historian who scrutinized more than four decades of CIA documents Sightings of unidentified flying objects from the late 1940s prompted intelligence officials to worry that the Soviets might try to disrupt U.S. air defense systems or the government itself by orchestrating mass UFO sightings, Gerald K. Haines writes. Such concerns, he said, prompted the Air Force and others to play down the issue and to concoct false cover stories to explain UFO sightings that were really super-secret U.S. spy planes -- the U-2 and the later SR-71 Blackbird.

Haines is a historian at the National Reconnaissance Office, which oversees missions and interprets data from the intelligence satellites that later replaced manned spy aircraft. His article, "CIA's Role in the Study of UFOs, 1947-90" was published in the spring issue of Studies of Intelligence, a CIA journal. An unclassified version has appeared on the Internet. Haines said a CIA study group worried in 1952 that panic and hysteria about UFO sightings might eventually "overload the U.S. air warning system so that it could not distinguish real (military) targets from phantom UFOs," providing the Soviets advantage for a surprise nuclear attack.

A special panel of outside scientists created to pursue such security implications concluded unanimously in 1953 that there was no credible evidence of UFOs from outer space, nor evidence of a direct national security threat, Haines wrote. But he said the scientists, headed by physicist H.P. Robertson of the California Institute of Technology, "did find that continued emphasis on UFO reporting might threaten the orderly functioning of the government by clogging the channels of communication with irrelevant reports and by inducing hysterical mass behavior harmful to constituted authority."

The panel recommended that the National Security Council "debunk UFO reports and institute a policy of public education to reassure the public of the lack of evidence behind UFOs." It also urged enlisting the mass media, advertising, business clubs and "even the Disney Corp. to get the message across," Haines wrote. By 1956, the Air Force was able to attribute 96 percent of all UFO sightings to the high altitude U-2 and SR-71 intelligence gathering planes, Haines said. But it took care "not to reveal the true cause of the sightings to the public," linking them instead to "natural phenomena such as ice crystals and temperature inversions." An Air Force spokesman, Maj. Ed Worley, said Sunday he could not comment specifically without first seeing the report. But he said, "We take extraordinary measures to protect our national resources." The original U-2s had silver bodies reflecting the sun's rays and sometimes causing those on the ground to see fiery objects, Haines wrote. Eventually they were painted black, as were the later Blackbird spy planes.

By steadfastly concealing its interest in the matter, the CIA itself "contributed to later charges of a CIA conspiracy and coverup," Haines said. Regardless, he said, "the UFO issue will probably not go away soon, no matter what the agency does or says" because "the belief that we are not alone in the universe is too emotionally appealing -- and the distrust of our government is too pervasive -- to make the issue amenable to, rational explanation and evidence." ON THE WEB - Haines' study can be found at www.odci.gov/csi/studies/97unclas/ufo.html