The article mentions that the Soviet Union had lots of titanium ore, and also that it was heavily used in the A-12/SR-71 family of aircraft.
I remember reading elsewhere that the CIA set up a bunch of front operations across the world to buy titanium (or maybe titanium ore) from the USSR without them finding out what it was being used for. They didn't want the "Ship to:" part of the order form reading "Lockheed Skunkworks, Burbank Califoria". Heh.
Elsewhere would of course be the excellent "Skunk Works: A Personal Memoir of My Years at Lockheed" by Ben Rich.
Highly reccomended and goes into further engineering and design challenges of the RS-71 Blackbird and its titanium construction.
There's an interesting story about trading Boeing aircraft design knowledge for Soviet titanium design knowledge during the cold war. https://www.smithsonianmag.com/air-space-magazine/the-titani...