From 1964 to 1966 Pérez de Cuéllar was Peruvian ambassador to Switzerland, and in 1969 he became his country's first ambassador to the Soviet Union. From 1971 to 1977 he was Peru's permanent representative to the UN. He chaired the UN Security Council in 1974, where he helped to mediate the protracted dispute over Cyprus between Greece and Turkey. After two years as ambassador to Venezuela, in 1979 he became UN undersecretary-general for special political affairs. As Secretary-General Kurt Waldheim's special representative, from April 1981 Pérez de Cuéllar attempted to defuse tensions between Afghanistan and Pakistan.
Elected secretary-general in December 1981 as a candidate acceptable to both the Western and Soviet blocs, Pérez de Cuéllar served two five-year terms, which coincided neatly with the ending of the Cold War. He encouraged the relaxation of Soviet-American tensions that began once Mikhail Gorbachev became Soviet general secretary in 1985. Pérez de Cuéllar believed that the new international climate gave new scope for the expansion of UN activities, ambitions largely stymied by the determination of the United States, under conservative Republican President Ronald Reagan, to cut rather than expand American contributions and dues to the UN on the grounds that the organization was plagued by waste, inefficiency, and a bloated bureaucracy.
Early in his tenure, Pérez de Cuéllar's efforts to mediate disputes between Argentina and Great Britain failed to prevent the 1982 Falklands (Malvinas) War. A staunch and widely respected advocate of negotiation, conciliation, and peacekeeping, he launched personal and ultimately successful initiatives, which Cold War de-escalation facilitated, to alleviate and end hostilities in Afghanistan, Namibia, and Lebanon and to relieve famine in Ethiopia. He also consistently emphasized refugee resettlement and human rights.
During 1987–1988, Pérez de Cuéllar took the lead in obtaining and implementing UN Resolution 598, which called for the cessation of hostilities in the lengthy and brutal Iran-Iraq War. Iraq's invasion of Kuwait in 1990 brought new challenges. UN Security Council Resolution 678 provided the legal basis for the coalition that ultimately drove Iraqi President Saddam Hussein's forces from Kuwait. Under Pérez de Cuéllar's leadership, the UN condemned Iraq's subsequent spring 1991 attacks on Kurdish rebels in northern Iraq, established a protective no-fly zone in that area, and ultimately took over control of Kurdish refugee camps there. Throughout his tenure as secretary-general, Pérez de Cuéllar displayed deft diplomatic skills and exhibited well-honed leadership in international crises.
Leaving office at the end of 1991, Pérez de Cuéllar accepted a visiting appointment at Yale University, where he wrote his memoirs. Looking ahead to the post–Cold War era, he urged the UN to move beyond international mediation and peacekeeping and focus on addressing social and economic problems and human rights abuses. In 1995 he ran unsuccessfully for president of Peru, losing to Alberto Fujimori. After Fujimori resigned on corruption charges, Pérez de Cuéllar served from November 2000 to July 2001 as foreign minister and president of Peru's Council of Ministers. He then became Peru's ambassador to France, where he remained after his final retirement in September 2004.
Lankevich, George J. The United Nations under Javier Pérez de Cuéllar, 1982–1991. Lanham, MD: Scarecrow, 2001.; Pérez de Cuéllar, Javier. Pilgrimage for Peace: A Secretary-General's Memoir. New York: St. Martin's, 1997.