I did a bit more reading about the A-12 after posting yesterday’s image. It was a slightly shorter, slightly faster version of the aircraft that eventually became the SR-71 Blackbird and was codenamed the rather unglamorous “Oxcart”. It was operated by the CIA as a surveillance platform in 1967 and 1968. This image shows a detail of the fuselage of the plane at the US Space and Rocket Center in Huntsville, Alabama.
For the technically inclined...