In May 1972, Richard Nixon travelled to Tehran and signed a deal with the shah of Iran that allowed the Iranian monarch to purchase any U.S. weapons system he desired, in any quantity, short of nuclear weapons. This so-called 'blank cheque' was a highly irregular move, and a revolutionary change in both U.S. arms sales policy and U.S.–Iran relations. It formed the major component of a new U.S. Persian Gulf policy and became a major application of the Nixon doctrine. Exploring in detail how and why this agreement came to pass form an important, and so far overlooked, episode in U.S. foreign policy.
McGlinchey, S. (2013). Richard Nixon’s Road to Tehran: The Making of the U.S.–Iran Arms Agreement of May 1972. Diplomatic History, 37(4), 841-860