Iraq–Syria relations are marked by a long-shared cultural and political links. There are many different forces at play in the region since the two countries became modern states after World War I when the border was established.
The two countries lie in what was once ancient Mesopotamia and political relations between them have often been hostile. Ever since King Faisal took the Iraqi throne in the early 1920s, Iraqi leaders have dreamed of unifying the two countries. Unity dreams only led to bad relations between other Arab states. Even during the thaw in Iraqi-Syrian relations during the last years of Saddam Hussein, relations between the two countries were not good. New diplomatic relations established in November 2006, were heralded as the beginning of an era of close cooperation between Iraq and Syria.
Ba'athist Iraq and Syria
Efforts by Syrians and Iraqis to unite Iraq and Syria into one country have existed since the creation of the modern states. Such unification efforts were to continue under the Ba'ath Party. Ironically enough, hostility between Syria and Iraq started in the 1966 when both were under Ba'athist rule. Relations improved in the early 1970s during the Yom Kippur War, but deteroriated again following Syria's acceptance of the UN sponsored ceasefire.
After the 1973 War, Syrian President Hafez al-Assad made several attempts in 1974 and 1975 to settle his differences with Iraq (arising from Syria's acceptance of UN Resolution 338 which lead to the ceasefire in the 1973 War; Iraq withdrew the expeditionary force it had sent to help Syria as a result of Syria's acceptance of the ceasefire) and establish a union between the two countries. Iraq however rejected Assad's offers and denounced him for his "readiness to make peace" with Israel. Strained relations between Iraq and Syria would continue up until 1978.
By October 1978, Iraq President, Ahmed Hassan al-Bakr began working closely with Assad to foil the Camp David Accords; signing in Baghdad a charter for Joint National Action which provided for the "closest form of unity ties" including "complete military unity" as well as "economic, political and cultural unification".
In 1978 Iraqi President Ahmed Hassan al-Bakr and Hafez al-Assad, had agreed to a plan and started to make treaties that would lead to the unification of Iraq and Syria. This plan was to come into effect in July 1979, however Saddam Hussein, the Deputy Secretary of the Iraqi Ba'ath Party, fearful of losing his power to Assad (who was supposed to become the deputy leader in the new union), forced al-Bakr into retirement under threat of violence.
Unity talks did continue between Assad and Hussein after July 1979, but Assad rejected Iraqi demands for a full merger between the two states and for the immediate deployment of Iraq troops into Syria. Instead Assad, perhaps fearful of Iraqi domination and a new war with Israel, advocated a step-by-step approach. The unity talks were eventually suspended indefinitely after an alleged discovery of a Syrian plot to overthrow Saddam Hussein in November 1979.
Shortly after coming to power Hussein claimed to have been informed of a plot against him, supported by the Syrians, and suspended, then later abandoned the plan for unification. In November 1979 both countries officially suspended relations with one another and withdrew their diplomatic missions. Prior to his forced retirement Bakr had expressed to Assad a desire to speed up the process of union, as he feared elements within the Iraqi Ba'ath Party were trying to kill the union plan. However the Iran-Iraq War and Assad's growing closeness with Iran effectively ended any hopes of rapprochement, and in January 1982 the borders between th two countries were closed and sealed and all trade and movement of citizens was stopped 
Later, Syria joined the coalition that liberated Kuwait from Iraqi occupation in the 1991 Gulf War. Up until the renewal of diplomatic ties in 2006, Iraqi leaders often accused Syria of trying to destabilize their country by allowing Sunni Arab foreign fighters to cross the border Iraq shares with Syria.
Relations with Syria have been marred by traditional rivalry for pre-eminence in Arab affairs, allegations of involvement in each other’s internal politics, and disputes over the waters of Euphrates River, oil transit fees, and stances toward Israel. Syria broke relations after Iraq invaded Kuwait in 1990 and joined other Arab states in sending military forces to the coalition that forced Iraq out of Kuwait. Relations remained cool until Bashar al-Assad became President of Syria in 2000.
Although the official relations between the two countries were suspended in the past, Syrian-Iraqi relations experienced developments in recent years and the reciprocal visits between the two countries have led to a number of agreements on economic cooperation including an agreement for resuming pumping of oil through the Syrian territories which was suspended in 1982.
Syria strongly opposed the occupation of Iraq in 2003, stressing the necessity to maintain the independence of Iraq and support its political process, demanding a time table for the withdrawal of the foreign troops from Iraq. Syria has also played the host for more than 2 million Iraqis, providing refuge for them.
Syria and Iraq formally ended more than twenty years of diplomatic estrangement, when Syria's foreign minister, Walid Muallem, visited Iraq in 2006, which was the first such meeting since the fall of Saddam Hussein in 2003. Ambassadors were established later in 2006. On 23 August 2009 the Iraqi government aired a taped conversation linking two members of the Syria-based Iraqi Ba'athist movement, Sattam Farhan and Mohammed Younis al-Ahmed, with the August 2009 Baghdad bombings which claimed more than 100 lives. The Syrian foreign ministry denied Syrian involvement in the attack. On 25 August Iraq summoned its ambassador to return from Syria, the Syrian government issued a similar order to its ambassador within hours in retaliation. Responsibility for the attack was later claimed by the Islamic State of Iraq, an al-Qaeda affiliate.
Syrian Civil War
Iraq abstained from voting to expel Syria from the League of Arab States. Iraq has maintained its embassy in Syria, while many others have closed. In March 2012, local lawmakers in Iraq’s Dohuk province voted Wednesday to open camp for refugees from Syria.
- Fertile Crescent Plan
- Foreign relations of Iraq
- Foreign relations of Syria
- Greater Syria (Region incorporating Iraq and Syria)
- Islamic State of Iraq and the Levant
- Shia Crescent
- Shia–Sunni relations
- Syrian Social Nationalist Party (Political party seeking the union of Iraq and Syria)
- Mughrabi, Maher (27 August 2014). "Iraq and Syria: the situation in six maps". The Sydney Morning Herald. Retrieved 3 September 2014.
- http://news.bbc.co.uk/2/hi/middle_east/6167968.stm Iraq and Syria restore relations
- Ma'oz, Moshe (1995). Syria and Israel : From War to Peacemaking. Oxford University Press. p. 153. ISBN 978-0-191-59086-3.
- Dawisha, Adeed (2009). Iraq: A Political History from Independence to Occupation. Princeton University Press. p. 214. ISBN 978-0-691-13957-9.
- McDonald, Michelle (2009). The Kiss of Saddam. University of Queensland Press. p. 128. ISBN 978-0-702-24359-2.
- "Iraq and Syria recall ambassadors". BBC. 25 August 2009. Retrieved 27 June 2009.
- "Iraq approves new refugee camp for Syrians fleeing bloody uprising against Assad regime", Washington Post