Overview
Most conspiracy theories about Area 51 run in one direction: the government is hiding alien craft and telling you they are experimental aircraft. This one runs the other way. It says the government was hiding experimental aircraft and was perfectly content to let you believe they were alien craft.
It is the more cynical reading, and it is the one with a paper trail.
The Aircraft
The U-2 first flew in 1955. It cruised above 70,000 feet at a time when commercial airliners operated around 20,000 and military aircraft rarely exceeded 40,000. Its long wings, at that altitude, caught sunlight from below the horizon after the sun had set for everyone on the ground, which meant airline pilots and observers in the early evening periodically saw a brilliant object, extremely high, moving fast, reflecting light that had no visible source.
They reported it. The reports went to the Air Force, which knew exactly what they were, and could not say.
The A-12 OXCART, flying from Groom Lake from 1962, made the problem worse. It operated higher still and above Mach 3, and its titanium skin heated to a glow across parts of the airframe.
What the Agency Published
In 1997 the CIA's Center for the Study of Intelligence published a study by its historian Gerald K. Haines, "CIA's Role in the Study of UFOs, 1947-90", in the classified-then-declassified journal Studies in Intelligence.
The passage that mattered was arithmetic. Haines wrote that over half of all UFO reports from the late 1950s through the 1960s were accounted for by manned reconnaissance flights over the United States — a figure he attributed to estimates from Agency officers who had worked on the U-2 and OXCART programmes. He then described the consequence: this led the Air Force to make misleading and deceptive statements to the public in order to allay public fears and to protect an extraordinarily sensitive national security project.
That is an official history, published by the organisation concerned, stating that the government knowingly issued false explanations for sightings its own aircraft had caused. The press coverage in August 1997 reported it in exactly those terms.
Project Blue Book
The mechanism was already in place. The Air Force ran a public investigation of unidentified flying objects from 1952 to 1969 under the name Project Blue Book, which collected thousands of reports and issued explanations — weather balloons, temperature inversions, the planet Venus, aircraft.
On the Haines account, a substantial share of the cases Blue Book was resolving with mundane explanations had a real and highly classified answer that the officers writing the resolutions were not cleared to give, and in some cases did not know. The programme closed in 1969 having concluded that nothing it examined threatened national security or represented technology beyond current knowledge — a statement that is entirely consistent with the aircraft explanation and reads very differently once you know it.
Where the Theory Goes Further
The documented part stops at explanation. The stronger version of the theory says the government did not merely permit the saucer interpretation but cultivated it — seeding stories, encouraging enthusiasts, treating a folk belief as a security asset because a population arguing about Martians is not asking about Nevada.
Evidence for deliberate cultivation is much thinner than for deliberate misdirection, and the two are easy to conflate. Issuing a false weather-balloon explanation is documented. Manufacturing a UFO subculture to absorb attention is an inference from the fact that one existed and was useful.
A related strand runs through the case of Paul Bennewitz, the Albuquerque businessman fed fabricated material about alien bases in the early 1980s by figures connected to the Air Force Office of Special Investigations, while he was monitoring signals near Kirtland Air Force Base. That episode is documented and has been acknowledged by participants, and it is the closest thing in the record to disinformation aimed at a specific believer rather than at the public.
The Two-Way Door
What gives this theory its unusual position is that it works for both audiences, which is why it appears on both sides of the argument.
For sceptics it explains the sightings without exotic physics: the objects were real, unusually fast, unusually high, and built in California. For believers it establishes something more useful — that the government has, by its own written admission, lied about what people saw in the sky, in a sustained way, for reasons it considered sufficient. Once that is on the record, every subsequent official explanation is available to be read as another one.
The Agency's historian, writing for an internal readership in 1997, presumably did not intend to supply that argument. It has been in circulation ever since.