US-A (Upravlenniye Sputnik Aktivny) were active radar satellites for ocean surveillance. The high power consumtion of the active radar required a nuclear reactor as power source. The satellites were known as RORSAT in the west. The US-AO series consisted of satellites, which tested all the system components but the nuclear reactor. They were battery powered.
The Soyuz/Vostok, also known as just Soyuz or Vostok, or by its GRAU index, 11A510 was an interim expendable carrier rocket used by the Soviet Union in 1965 and 1966. Two were launched with prototype US-A satellites.