Apollo-Soyuz Test Project. US and USSR both launched manned spacecrafts on 15th July 1975. The Apollo spacecraft successfully docked with the Soyuz on 17th July 1975. Three hours later, the two mission commanders, Thomas Stafford and Alexei Leonov, exchanged the first international handshake in space through the open hatch of the Soyuz.
Apollo-Soyuz signed document, known as the Space Magna Carta; the first official official government document signed in space. In English and Russian dated July 17, 1975.
FIRST INTERNATIONAL SPACE DOCKING CERTIFICATE This is to certify that at 12 hours 09 minutes Washington time and 19 hours 09 minutes Moscow time, on July 17 1975, flight crews of the United States of America and the Soviet Socialist Republic successfully docked their Apollo and Soyuz spacecraft in Earth orbit. They share the hope that this first international manned space flight will stand in the light of history as a significant advance in the ability of their nations to work together in ways that advance the interests of people everywhere.
This official government document was signed by the two entire crews, including Thomas P. Stafford, D. K. Slayton, Vance Brand, Alexey Leonov, and Valerie Kubasov. This document was the start of the cooperation in space between the U.S. and Russian programs, and the beginning of the end of the Cold War and the eventual demise of the old Soviet Union.