The ironic part is, during the "cold war" US had to buy the titanium used to make them from Russia since we didn't have enough in our own country or our friends to build them. CIA created a shell company to make the Russian buy. The J58s were modified to basically turn into a ramjet somewhere above mach 2 and everything changed at that point. They ran on JP7 which was pumped through the hydraulics before it got to the engines. Some amazing engineering for its time!!