"Ah! My dear Watson, there we come into those realms of conjecture, where the most logical mind may be at fault. Each may form his own hypothesis upon the present evidence, and yours is as likely to be correct as mine."
(The Adventure of the Empty House by Sir Arthur Conan Doyle)

Declassified Defense Intelligence Agency documents released under the Freedom of Information Act reveal that on 19 September, 1976, an unusual incident occurred over Tehran, Iran.

At about 0030 hours, the Shah's Imperial Iranian Air Force command post at Tehran received four telephone reports from citizens in the Shemiran area of the city. Some of the callers reported seeing a bird-like object in the sky, while others reported a helicopter with a bright light. When the command post found that there were no helicopters airborne at that time, they called BG Yousefi, assistant deputy commander of operations.Yousefi at first said the object was only a star, but after talking to the tower at Mehrabad Airport, he looked for himself and saw a very bright object larger than a star. At that point he decided to scramble an F-4 jet from Shahrokhi AFB.

At 0130 hours, the F-4 took off and proceeded to a point 40 nautical miles north of Tehran. It was noted that the object was of such brilliance that it could be seen up to 70 miles away. When the F-4 came to within about 25 nautical miles of the object, the jet suddenly lost all instrumentation and communications. The pilot broke off the intercept and turned away. When the F-4 had turned back towrd Sharokhi, the aircraft regained instrumentation and communication.

At 0140 hours, a second F-4 was scrambled and it acquired a radar lock on the object at 27 nautical miles range, closing on the object at 150 nautical miles per hour. At a range of 25 nautical miles, the object began to move, keeping a steady distance of 25 nautical miles from the F-4.

The size of the object was difficult to determine due to its intense brilliance, but the radar return was comparable to that of a 707 tanker. The lights of the object were alternating blue, green, red, and orange, and were arranged in a square pattern. The lights flashed in sequence, but the flashing was so rapid that they all could be seen at once.

As the object and the F-4 countinued on a southerly path, a smaller second object detached itself from the first and advanced on the F-4 at a high rate of speed. Thinking himself to be under attack, the F-4 pilot attempted to launch an AIM-9 missile, but he suddenly lost all instrumentation, including weapons control, and all communication. The F-4 pilot then instituted a turn and a negative G dive as evasive action. The object fell in behind him at about 3 to 4 nautical miles distance for a short time, then turned and rejoined the primary object.

Once again, as soon as the F-4 had turned away, instrumentation and communications were regained. The F-4 crew then saw another brightly lit object detach itself from the other side of the primary object and drop straight down at a high rate of speed. The F-4 crew expected it to impact the ground and explode, but it came to rest gently. The F-4 crew then overflew the site at a decreased altitude and marked the position of the light's touchdown. They then landed at Mehrabad, noting that each time they passed through a magnetic bearing of 150 degrees from Mehrabad, they experienced interference and experienced communications failure. A civilian airliner that was approaching Mehrabad experienced a loss of communications at the same position relative to Mehrabad. As the F-4 was on final approach, they sighted yet another object, cylinder-shaped, with bright, steady lights on each end and a flashing light in the middle. Mehrabad tower reported no other aircraft in the area, but tower personnel were able to see the object when given direction by the F-4 pilot.

The next day, the F-4 crew flew out in a helicopter to the site where they had seen the smaller object land. In the daylight, it was determined to be a dry lake bed, but no traces could be seen. They then circled the area to the west and picked up a noticeable "beeper" signal. The signal was loudest near a small house, so they landed and questioned the occupants of the house about any unusual events of the previous night. They reported a loud noise and a bright light like lightning.

Further investigation of the landing site, including radiation testing of the area was apparently done, but the results were never made public. Since this event occured before the fall of the Shah, any records in Tehran itself may be lost.

The Defense Intelligence Agency itself called this report:

An outstanding report. This case is a classic which meets all the criteria necessary for a valid study of the UFO phenomenon...

One of the most interesting things about this event is that it was apparently detected by a military spy satellite. This satellite, the DSP-1, was launched to warn of ballistic missile launches by detecting infrared heat sources. It was used to detect SCUD missile launches during Desert Storm. An analysis of computer printouts from DSP-1 by researchers Lee Graham and Ron Reghr, of Aero-Jet in California, shows that it definitely detected an infrared anomaly over Tehran at the time of the UFO event reported above.