Zbigniew Kazimierz Brzezinski ( ;   ; born March 28, 1928) is a Polish-American political scientist and geostrategist, who served as a counselor to President Lyndon B. Johnson from 1966–68 and was President Jimmy Carter's National Security Advisor from 1977–81. Brzezinski belongs to the realist school of international relations, standing in the geopolitical tradition of Halford Mackinder and Nicholas J. Spykman.