Richard Nixon was the first US president since WW2 to visit the Soviet Union. He arrived on Moscow in May 22, 1972. On May 26, Richard Nixon and Leonid Brezhnev signed the Strategic Arms Limitation Treaty ( SALT 1 ). The main goal of SALT 1 was to limit the growth of the nuclear arsenal of both superpowers. Nixon and Brezhnev also made agreement about the joint space flight in 1975.
Answer: Brezhnev invited Nixon to visit Moscow because he wanted to sign the SALT 1 treaty with him.