The 1975 Algiers Agreement (commonly known as the Algiers Accord, sometimes as the Algiers Declaration) was an agreement between Iran and Iraq to settle their border disputes and conflicts (such as the Shatt al-Arab, known as Arvand Rud in Iran), and it served as basis for the bilateral treaties signed on 13 June and 26 December 1975. The agreement was meant to end the disputes between Iraq and Iran on their borders in Shatt al-Arab and Khuzestan, but the main reason for Iraq was to end the Kurdish rebellion. Less than six years after signing the treaty, on 17 September 1980, Iraq abolished the treaty but under international law, one nation cannot unilaterally reject a previously ratified treaty, and the treaty had no clause providing for abrogation by one nation only.
Friction remains along the border despite the currently binding treaty and its detailed boundary delimitation remaining in force since it was signed in 1975 and ratified in 1976 by both nations.
In 1963, after the Ramadan Revolution, the Ba'ath Party led government being headed by Ahmad Hassan al-Bakr, launched a campaign against the Kurdish rebellion, that was looking for independence from Iraq. The Ba'ath led government fell after the November 1963 coup led by Abdul Salam Arif. The relations between the government and Kurds didn't reach any final decisions. In 1968, the Ba'ath Party started another revolution, the 17 July Revolution. The relations between the Iraqis and Kurds became tense, with the Iraqi Armed Forces suppressing the Kurdish movement. The Kurdish rebels caused massive economical damage to the Iraqi government. On 11 March 1970, a treaty was signed between the Vice-Chairman of the Revolutionary Command Council (Iraq), Saddam Hussein, called the "March Manifesto" and the leader of the Kurdish rebellion, Mustafa al-Barzani, in Tikrit, to end the conflict. The treaty states that the Kurdish militias get merged with the Iraqi Army, cut the ties between Iran and the Kurds and put an end to the rebellion. In return, the Iraqi government promised the Kurds autonomy, with Kurdish persons included in the Iraqi government. The government encouraged the "Arabization" of the Oil-rich Kurdish regions. In 1974, there were lots of problems between the government and the Kurds about the Oil of Iraq. The Kurdish ministers left the government, the Kurdish employees left their jobs and Kurdish police and soldiers left the army. The Iraqi government demanded the Kurds to implement the treaty, but they refused. On 11 March 1974, the manifesto became a law in the Iraqi constitution. After that, the fight between the Iraqi army and Kurdish forces continued, with Iran supporting the Kurds.
After the Ba'ath Party rose to power, in 1968, the Iraqi government demanded full control over Shatt al-Arab. On 19 April 1969, Iran abolished the 1937 agreement, which was signed between Iraq and Iran to sort the border problems, with a weak excuse, that Iraq provoked Iranian boats sailing in Shatt al-Arab. In April 1969, both armies were deployed on the banks of the Persian Gulf. After Iran took control of four islands in the Persian Gulf, Baghdad had lots of diplomatic problems with Tehran. Iraq called the Arabs of Khuzestan to start an uprising against the Shah of Iran Mohammed Reza Pahlavi. Iraq also kicked all the Iranians out of Iraq. Iran supported the Kurds in the Iraqi–Kurdish War with military equipment and funded them with money. Mustafa al-Barzani met with representatives from the American government to support the Kurds secretly, so, the Iraqi position wasn't good, especially after the outbreak of the Yom Kippur War. Iraq wanted to build a new diplomatic structure with Iran, fearing that Iran will attack them from the east, while most of the Iraqi Armed Forces are fighting on the Syrian Front.
Since 1973, Iraq started negotiating with Iran, hoping that it would stop its support to the Kurdish rebels. In late April, a meeting was held in Geneva between the country's foreign ministers. Iraqi representatives insisted on reactivate the 1937 treaty, which gives most of Shatt al-Arab to Iraq, but Iranian representatives refused. After the discussions failed, meetings were held between the two countries. Mohammed Reza Pahlavi decided to show no flexibility, and was determined to take control over exactly half of Shatt al-Arab. After the Shatt al-Arab discussions were made, Iraq started discussing ending the Iranian support to the Kurds.
In May 1974, Iraq and Iran started a committee to mark the Shatt al-Arab boundary between them. In the 1974 Arab League summit, representatives from Iran's government attended to talk with Iraqi representatives with the mediation of King of Jordan Hussein. Talks continued between the two countries sporadically, because Iraq was reluctant to give up his territorial demands. Iran started increasing its support of the Kurds, which led the Iraqi Army to fold. Saddam Hussein and Mohammed Reza Pahlavi attended the OPEC summit in Algiers on 6 March 1975, where they agreed on an agreement and signed it with the mediation of Houari Boumediene.
The agreement was important to Iraq in order to end the Kurdish War and to end the violence near Shatt al-Arab with Iran. It was also in Iran's interest because the Iraqi Army had taken control of lots of Kurdish areas, in the summer of 1974, and the Kurdish rebels had failed to get them back. Also Mohammed Reza Pahlavi did not want the Iranian Army to get too involved in conflict, avoiding a full-scale war with Iraq.
Algiers Agreement determined that the border between Iraq and Iran in Shatt al-Arab will be the centerline (thalweg) of it. The border will be determined accordingly to the Treaty of Constantinople (1913) to relinquish its relations to Arab areas in Western Iran. Areas of Iraq are intended to provide some strategic depth was missing from an Iranian attack. In addition, the two countries will "commit themselves to maintain close and effective supervision over their common boundary to end insidious nature intrusions from every possible source." In other words, Iran is undertaking the possibility of stopping their support to the Kurds. The both countries agreed to return to being two good neighboring countries. A violation of one part of the agreement "contradicts the spirit of Algiers Agreement."
On 15 March 1975, the Iraqi and Iranian foreign ministers met with the Algerian representatives to establish a joint committee to mark the new borders. On 17 March, the protocol between the two countries was signed by the two foreign ministers. The protocol states that the two countries undertakes re-mark the border.
On 13 June 1975, another treaty was signed in Baghdad by Iraq's and Iran's foreign ministers. It involved a lot of parts about conflicts between them and the placement of the borders and its changes. The treaty is called "Iraq-Iran international borders and good neighborly relations."
Iraq and Iran formed a joint commission to mark the boundary between the two countries. They set up headquarters in all over the border. The commission ended marking the border on 26 December 1975 with the signing of a joint declaration of intents. Iran pulled back all of its soldiers from Iraq and sealed the borders, after stopping the support of the Kurds, suddenly, without any declaration. Iran also requested the CIA and the Mossad to end the military support of the Kurdish rebels. Most of the people thought that after the end of international support, the Iraqi government would negotiate with the Kurds, but the Vice-Chairman of Revolutionary Command Council, Saddam Hussein, launched an aggressive campaign against the rebels to end them forever. Mohammed Reza Pahlavi interfered and succeeded in establishing a cease fire, but on 1 April, the government relaunched the campaign. After many battles, the Iraqi Armed Forces finally defeated the rebels and ended the rebellion. More than 100,000 Kurdish refugees fled to Iran and Turkey with their leader, Mustafa al-Barzani, only to come back with another much more violent rebellion in 1978.
In 1979, the Islamic Revolution in Iran made Khomeini the country's leader. Khomeini wanted to "spread the revolution to the Islamic world", including Iraq to free its people from the "dictatorship." Iraq abolished the Algiers Agreement on 17 September 1980, which led to the longest war in the region in the 20th century, the Iraq-Iran War. The war lasted 8 years until the United Nations Security Council Resolution 619 ended the war and returned both parties to the Algiers Agreement of 1975.