Call of Duty: Black Ops takes place during the Cold War, in the 1960s. The story focuses on the CIA's Special Activities Division (SAD) Studies and Observations Group (SOG) (originally and currently called "Special Operations Group") - backed clandestine black operations carried out behind enemy lines. These missions take place in various locations around the globe such as the Ural Mountains in central Russia, Cuba, Laos, and Vietnam. The single-player campaign revolves around an experimental Soviet chemical weapon codenamed "Nova-6".
The player mainly controls SAD/SOG special forces operative Alex Mason and occasionally CIA agent Jason Hudson, as well as other characters. Mason often works with Frank Woods and Joseph Bowman, while Hudson teams up with Grigori Weaver, a Russian-born field operative. Viktor Reznov, a key character from the Soviet campaign in World at War returns. Its Russian protagonist Dimitri Petrenko also makes an appearance. Black Ops features several historical figures: Mason meets John F. Kennedy, Robert McNamara, and Fidel Castro.