After attending the Catholic University in Lima, Pérez de Cuellar joined the foreign ministry in 1940 and the diplomatic service in 1944. After serving in embassies in France, the United Kingdom, Bolivia, and Brazil, he returned in 1961 to the Ministry of Foreign Affairs, where he remained until 1969 (except for a two-year term, 1964?66, as ambassador to Switzerland). After serving as Peru’s first ambassador to the Soviet Union (1969?71), he was made Peru’s permanent representative to the UN, a post that he held until becoming secretary-general on Jan. 1, 1982, succeeding Kurt Waldheim in that post.
Pérez de Cuellar repeatedly advocated the use of the UN Security Council for keeping the peace and serving as a forum for negotiations. He was reelected to another five-year term as secretary-general in 1986. In August 1988 Pérez de Cuellar personally negotiated the cease-fire that ended active hostilities in the Iran-Iraq War.
Pérez de Cuellar was a skilled diplomat. He was the author of Manual de Derecho Diplomático (1964; ?Manual of Diplomatic Law?).
“Pérez de Cuellar, Javier” Encyclopædia Britannica