Which mission symbolically concluded the competitive standoff phase of the Space Race and set groundwork for the ISS?

Answer

Apollo-Soyuz mission in 1975.

The Apollo-Soyuz mission in 1975 symbolically ended the competitive standoff between the U.S. and the Soviet Union and laid the groundwork for subsequent joint projects like the International Space Station (ISS).

Which mission symbolically concluded the competitive standoff phase of the Space Race and set groundwork for the ISS?
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