The U.S. State Department Central Files are the definitive source of American diplomatic reporting on political, military, social, and economic developments throughout the world in the 20th century. Concentrating exclusively on those Central Files that have not been microfilmed by the National Archives or other publishers, UPA's microfilm editions of the Central Files nonetheless dwarf the State Department's very selective volumes of the Foreign Relations of the United States (FRUS). Containing less than one percent of the material in the Central Files, FRUS focuses on U.S. relations with individual countries but does not include coverage of many of the key topics to which the majority of the original files are devoted. Each part of the Central Files contains a wide range of materials from U.S. diplomats in foreign countries: special reports on political and military affairs; studies and statistics on socioeconomic matters; interviews and minutes of meetings with foreign government officials; court proceedings and other legal documents; full texts of important letters, instructions, and cables sent and received by U.S. diplomatic personnel; voluminous reports and translations from foreign journals and newspapers; and countless translations of high-level foreign government documents. Here are the documents that tell what the U.S. State Department knew about the repressive nature of the shah's rule and the degree of popular support he enjoyed. Martial law, imposed after Mohammad Mosaddeq's overthrow in 1953, was maintained until 1957. As the collection details, the shah continued to exercise strict political controls even after ending martial law. In 1955, Iran entered the Baghdad Pact with Britain, Iraq, Turkey, and Pakistan. In March 1959, Iran signed a bilateral defense agreement with the United States. The Central Files offer insights into the shah's desire for close relations with the United States-which resulted in these alliances-and into his requests for U.S. military and economic aid.