Design of commercial supersonic aircraft began in the early 1960s when U.S. companies coupled experience from military vehicles and commercial jetliner programs to design the prototype U.S. SST. Almost concurrently, the U.S.S.R. initiated its SST program leading to the TU-144, and a British and French consortium initiated work on the Concorde. Boeing continued development of the U.S. SST until 1971, when the U.S. federal government canceled the prototype program because of increasing concerns over its economic viability and environmental issues. No U.S. manufacturer was willing to continue the program without Government funding because of the market risks associated with the unsolved problems of poor economics and possible environmental problems.