The international relations of Iran in this century have been marked by major ruptures. These have been the consequence both of external intervention and shifts in international alignment and of internal changes which, while often influenced by external factors, have also had roots within Iranian society and politics themselves. One point of rupture, when internal upheaval intersected external influence, came with the period of the Constitutional Revolution and the 1907 Anglo-Soviet delimitation of spheres of influence. Another break, equally a product of the internal and the external, was the First World War and the subsequent emergence of Reza Khan as ruler in 1921. Twenty years later, in 1941, Russia and Britain removed Reza Khan and turmoil followed until the coup which put his son, Mohammed Reza Pahlavi, back into power in 1953. Twenty-six years later, the apparently secure regime re-established in 1953 was swept away in the Iranian revolution out of which emerged the Islamic Republic. In short-term perspective, the revolution of 1979 appeared to interrupt a hitherto stable society: in the longer perspective, it was but the latest of the upheavals that have punctuated modem Iranian history and international relations, and may well not be the last.!