The treaty established the waterway border on the eastern bank of the river except for a four-mile anchorage zone near Abadan, which was allotted to Iran and where the border ran along the thalweg. Iran sent a delegation to Iraqi Republic soon after the Ba'ath coup in 1969 and, when Iraq refused to proceed with negotiations over a new treaty, the treaty of 1937 was withdrawn by Iran. The Iranian abrogation of the 1937 treaty marked the beginning of a period of acute Iraqi-Iranian tension that was to last until the Algiers Accords of 1975.[1]