In 1967 and 1968 space treaties were signed by the two countries (USA and Soviet Union) that would allow for joint rescue of astronauts/cosmonauts and the return of space objects to their country of origin. In fact, during the Apollo 13 mission in April 1970, the Soviet Union offered assistance...
Other countries in the world have powerful telescopes and electronic equipment. Australia has confirmed the hardware left behind on the moon, lunar buggy etc, can still be seen.