A full 100 years after Nelson Mandela’s July 18, 1918, birth, he is remembered around the world as a symbol of peace and freedom, for ushering South Africa into a democratic, post-apartheid future.

Yet throughout his life, Mandela had a habit of saying that he was “not a saint,” as TIME noted in his 2013 obituary. Perhaps more surprisingly from today’s perspective, many people around the world felt the same way. In fact, Mandela remained on U.S. terrorist watch lists until 2008.

Understanding the reasons behind that fact requires seeing Mandela’s life and work in the context of both the history of the African National Congress (ANC), the political party with which Mandela was associated, and the history of United States attitudes during the Cold War.