Case 172 took place in a "sparsely populated" part of the country like so many UFO incidents, by conducting tests in the countryside the program mitigated the risks of radiation exposure and there would be less witnesses who could blow the cover of the program. It was government policy during the early years of the U-2 program, which also had a nuclear variant, to force witnesses to sign non-disclosure agreements. Airline passengers who saw the U-2 were forced by the FBI sign non-disclosure agreements.
23 February 1947
Project SIGN Case Number: 172
The third most publicly celebrated UFO case of the Project SIGN period would again involve one of the military’s own personnel. A drama would be played out in the North Central area of the United
States. In a sparsely populated area of the country a modern cowboy would face a showdown with an unidentified flying object. This case would be listed in the Project SIGN files as Incident Number 172, and to be commonly known as, "The UFO Dogfight over Fargo." When the team from Project SIGN arrived they checked out Gorman’s aircraft with a Geiger Counter. The aircraft showed signs of radiation. Unfortunately, the team would later discard this aspect of the incident.
25 November 1949
Mt. Palomar, California
Flying Discs Activate Geiger Counters Fran Ridge:
Nov. 25, 1949; Mt. Palomar, California
Flying discs first observed near the observatory at Mt. Palomar. A recording geiger counter was so activated at the times of these sightings, that it went completely off scale. Written off as an equipment malfunction, a loose fuse clip. Not only would this turn the equipment off, instead of on, the Project Record Card mentions a radar tracking.
The Soviet Ministry of Defence established a top-secret group (committee) for studying UFOs at Kapustin Yar. A special UFO archive was opened at Krasny Kut in Saratov Region (in an underground bunker in the special zone of Beryozovka 2). The archive was opened as a direct result of the appearance of several UFOs over Krasny Kut and Kapustin Yar in 1954 and the disappearance of the fighters sent to intercept them. http://www.rusartnet.com/russia/history/world/ufos-in-russia