The longest continuing United States classified military airplane program is the testing and evaluation of Foreign Aircraft Technology. During the Cold War, secret test flying of Mikoyan-and-Gurevich Design Bureau (MiG) and other Soviet aircraft was an ongoing mission dating back to the acquisition of the first Soviet-built Yakovlev Yak-23 in 1953. This effort has continued to the present day. Unlike the other "black" airplane programs, such as the Have Blue, Lockheed U-2, or SR-71 Blackbird, Foreign Aircraft Technology operations still remain classified. Despite the declassification of the Constant Peg program in the early 2000s, the evaluation of Foreign aircraft likely continues.