[thmorton]

To prevent them from falling into the wrong hands and another nation building an SR-71:

> In 1968, a presidential order required that all molds and tools used to build the SR-71 be destroyed so that the plane could never be built by anyone again. This also meant that spare parts could not be made, so if there were any major problems, planes in storage would have to be cannibalized. http://www.strategic-air-command.com/aircraft/reconnaissance...

> 8. How many SR-71's were built? 50 Blackbird airframes of various designations. The dies or molds were destroyed as directed by then Secretary of Defense McNamara to prevent any other nation from building the aircraft. http://www.wvi.com/~sr71webmaster/srqt~1.htm