 George Frost Kennan ( February 16 , 1904 – March 17 , 2005 ) was an American diplomat and historian . He was known best as an advocate of a policy of containment of Soviet expansion during the Cold War on which he later reversed himself . He lectured widely and wrote scholarly histories of the relations between USSR and the United States . He was the only person to have served as both Director of Policy Planning at the State Department and Director of the Office of National Estimates at the CIA .

## Biography

George Kennan was born in Milwaukee , Wisconsin , to John Niles Kennan and his second wife