Popovich was a Russian terrorist leader. Nikitich worked for him and he also had ties to Abu Bahaa. Mustang Squad attacked his base in To The Summit 1 and 2. He tried to escape his Cold War Era bunker in a submarine. Newman destroyed it and captured Popovich. Before they were able to escape with him, he pulled a gun on them and more of his soldiers came to help him. He turned Mustang Squad over to Pablo, who imprisoned them in his South American Compund.