The Central Intelligence Agency’s A-12 OXCART reconnaissance aircraft, developed by Lockheed’s Skunk Works as the successor to the U-2 spy plane, was designed specifically to avoid Soviet Union air defenses during the Cold War. In order to meet the speed and altitude requirements, the OXCART team “overcame numerous technical challenges with cutting-edge innovations in titanium fabrication, lubricants, jet engines, fuel, navigation, flight control, electronic countermeasures, radar stealthiness, and pilot life-support systems,” according to the CIA Museum. The A-12 was officially declared fully operational in 1965, with its first deployment coming two years later.
The A-12 operational lifetime was short-lived, however, as the CORONA reconnaissance satellite, which was first launched in June 1959, began providing worldwide imagery without much of the risk associated with airborne reconnaissance. At the same time, the U.S. Air Force’s overt SR‑71, a modified version of the covert A-12, began operations, leading to the A-12's retirement in 1968.
According to the CIA Museum, the “A-12 represents a pioneering achievement in aeronautical engineering and, to this day, holds records for speed and altitude (Mach 3.29 at 90,000 feet) for an air-breathing piloted jet aircraft.”