The United States secretly acquired a Soviet MiG-21 jet fighter from Israel and tested it at the notorious Area 51 base deep in the Nevada desert, according to the U.K. newspaper The Guardian.



The plane was "originally obtained" by Israel in August 1966, at the height of the Cold War, the paper said, without providing further details. Between January and April 1968 it was loaned to the U.S., where it was known as the YF-110.



The U.S. Air Force examined the plane’s technical characteristics and evaluated its performance to see how U.S. weapons and aircraft compared tactically. Similar evaluations were conducted in 1969 with the MiG-17. The Guardian wrote that additional MiG examinations had taken place subsequently, but details remained classified.

As part of the air force’s evaluation of Soviet air capabilities, the military group would simulate a Soviet-style air defense complex made out of systems with names including Mary, Susan and Kathy, the paper wrote.

The Guardian's information was based on documents released Tuesday that shed light on the once-classified and long speculated base deep in the Nevada desert. The existence of Area 51, which had long been rumoured, was confirmed by the CIA in August when it released declassified documents through a Freedom of Information Act request by George Washington University's National Security Archive.



The initial documents show that Area 51 was used to test the U.S. government’s aerial programs.



The site was eventually transferred from the CIA to the air force in the late-1970s and became widely known in the mid-1990s.



Area 51 was discovered by government staffers and Lockheed Martin employees who thought it would be a good place to test aircraft while flying over Nevada, according to the first batch of documents.



Archive senior fellow Jeffrey T. Richelson was able to review the documents in 2002, but mentions of Area 51 were redacted at the time. He submitted a request for the CIA’s history again in 2005 to continue his research on aerial surveillance programs.



Open gallery view Warning sign outside Area 51 in Nevada. Credit: Wikipedia Commons