The Lockheed D-21 was an American Mach 3+ reconnaissance drone. The D-21 was initially designed to be launched from the back of its M-21 carrier aircraft, a variant of the Lockheed A-12 aircraft. An M-21 (specifically, a YF-12A Black Bird prototype) was used to transport a D-21 drone into Tselinoyarsk, during Operation Snake Eater in August 1964. The drone was used to insert Naked Snake into the area, due to heightened security. It was rigged to have its technologically-sensitive components self-destruct when the enemy was near in order to ensure the Soviets couldn't replicate the technology, although it was deliberately given U.S. markings to ensure that the Soviets knew of America's involvement, as part of negotiations with Nikita Khrushchev. Despite a successful landing, Snake felt that