"The United States and Iran are the two key players in the fight against ISIS, not least of all because they are two of the group's main targets. Indeed, other countries, particularly in Europe, have also been targeted by the group and seen ISIS attempt to recruit among their populations. As a result, they also share an interest in combatting the group. But the United States and Iran have made the fight against ISIS a security policy priority and allocated considerable resources to undertaking efforts in Iraq and Syria. While the two adversaries have aligned interests in Iraq, they have undertaken separate counterterrorism efforts to tackle the group."

This article assesses Iran's strategy in dealing with the threat of the Islamic State in Iraq and Syria (ISIS). It examines the implications of the rise of ISIS in Iran's immediate neighbourhood for Tehran's policies in Syria and Iraq and investigates how each of these countries affects Iranian national interests. It provides an overview of the major events marking Iran and Iraq's relations in the past few decades and discusses the strategic importance of Iraq for Iran, by looking at the two countries' energy, economic and religious ties. It also considers Iran's involvement in Syria since the beginning of the Syrian conflict.