Richard F. Pedersen, a United States diplomat who left a career imbued with cold war politics to become president of the American University in Cairo, died on July 11 at his home in Greenport, Long Island. He was 86.

His wife, Nelda, confirmed the death.

Mr. Pedersen’s government career of more than 20 years encompassed posts at the United Nations and the State Department and in Hungary, where he was the United States ambassador. At the United Nations, starting in 1953, he worked under five United States ambassadors, including Henry Cabot Lodge Jr. in the Eisenhower administration and Adlai E. Stevenson under President John F. Kennedy, assisting Mr. Stevenson in tense negotiations during the Cuban missile crisis in 1962....