Iraq and Iran have disputed navigation rights on the Shatt al Arab since 1935, when an international commission gave Iraq total control of the Shatt al Arab, leaving Iran with control only of the approaches to Abadan and Khorramshahr, its chief ports, and unable to develop new port facilities in the delta. To preclude Iraqi political pressure and interference with its oil and freight shipments on the Shatt al Arab, Iran built ports on the Persian Gulf to handle foreign trade. Iran and Iraq negotiated territorial agreements over the Shatt al Arab waterway in 1975, but by the end of the decade skirmishes in the area became prevalent. Full-scale war between the two countries broke out in Sept., 1980, leading to eight years of attacks on coastal areas (see Iran-Iraq War). The Shatt al Arab remains a source of conflict, as limited water access and unresolved maritime boundaries in the region persist.