In 1981, North Korea made an attempt to attack an S-71 using a Soviet S-75 Dvina missile. This is a missile that was in use since 1957 and capable of travelling at Mach 3.5 and altitude of 82,000 feet.
The SR-71 flew over the Demilitarized Zone of North and South Korea. During the first flight there was no launching of a missile. North Korea later launched an S-75 but this also fell short by a few miles. In the same year, the SR71 travelled the same route but no missile was launched.
The SR-71 was highly advantaged in speed and height. It flew at Mach 3.3 and 80,000 feet and it was extremely difficult to be caught by a missile. The aircraft was capable of adjusting its route in order to keep pace. At that pace and in the air it was nearly impossible to strike–it was quicker than a rifle bullet in the sky.
