The Shatt al-Arab (Arabic: شط العرب) or Arvand (called اروندرود: arvandrūd in Persian), also called the Shatt-al-Arab waterway, is a river in Southwest Asia of some 200 km in length, formed by the confluence of the Euphrates and the Tigris in southern Iraq. At the southern end of the river it constitutes the border between Iraq and Iran down to the mouth of the river as it discharges into the Persian Gulf. Conflicting territorial claims and disputes over navigation rights between these two countries were among the main factors for the Iraq-Iran War that lasted from 1980 to 1988, when the pre-1980 status quo was restored. The city of Basra along this river is Iraq's major port.
Control of the waterway and its use as a border have been a source of contention between the predecessors of the Iranian and Iraqi states since a peace treaty signed in 1639 between the Persian and the Ottoman Empires, which divided the territory according to tribal customs and loyalties, without attempting a rigorous land survey. The tribes on both sides of the lower waterway, however, are Marsh Arabs, and the Ottoman Empire claimed to represent them. Tensions between the opposing empires that extended across a wide range of religious, cultural and political conflicts, led to the outbreak of hostilities in the 19th century and eventually yielded the Second Treaty of Erzerum between the two parties, in 1847, after protracted negotiations, which included British and Russian delagates. Even afterwards, backtracking and disagreements continued, until British Foreign Secretary, Lord Palmerston, was moved to comment in 1851 that "the boundary line between Turkey and Persia can never be finally settled except by an arbitrary decision on the part of Great Britain and Russia". A protocol between the Young Turks and the Persians was signed in Constantinople in 1913, but World War I cancelled all plans.
The British advisors in Iraq were able to keep the waterway bi-national under the thalweg principle that has worked in Europe (see Danube River): the dividing line was the middle of the waterway. All United Nations attempts to intervene as mediators were rebuffed. Under Saddam Hussein Baathist Iraq claimed the 200-kilometer navigable channel up to the Iranian shore as its territory. But in 1975, Iraq signed the Algiers Accord in which it recognized the line running down the middle of the waterway, as the official border. However, in 1980 Iraq invaded Iran, thus breaking its part of the bargain. The main thrust of the military movement on the ground was across the Shatt al_Arab. Later, and as the Persian Gulf War was looming, Saddam again recognized the Algiers Accord in order to appease Iranians before he could undertake an invasion of Kuwait.
During the occupation of Iraq, British servicemen were held for two days in June 2004 after apparently straying into the Iranian side of the Shatt al-Arab. After being initially threatened with prosecution, they were released after high level conversations between British Foreign Secretary, Jack Straw, and Iranian Minister of Foreign Affairs, Kamal Kharrazi. The initial hardline approach was put down to power struggles within the Iranian government. The British marines' weapons and boats were confiscated.
- ICE case:Iran-Iraq War and Waterway rights (http://www.american.edu/projects/mandala/TED/ice/IRANIRAQ.HTM)
- The Iran-Iraq border, 1840 - 1958, archive (http://www.archiveeditions.co.uk/Leafcopy/160-5.htm)