Despite politically driven rhetoric touting the virtues of “going it alone” in foreign policy, cooperation with other nations in its various forms remains essential to countering terrorism. The Islamic State (also known as ISIS) may be on the run within Iraq and Syria, but its affiliates and other terrorist groups such as al Qaeda still represent a significant threat to international security. Because such groups span countries, communities, and borders, international cooperation to defeat them has been critical.
In a recent report, we used game theory and related methods to assess the likelihood of ISIS’ defeat. We found that if the international trend toward isolationism continues, ISIS’ destruction will become less likely—and as terrorism continues from al Qaeda and other groups, international cooperation will be just as relevant to ISIS’ successor. However, if countries and firms band together and share resources, they can succeed.
The benefits of multilateral cooperation against terrorism are readily apparent. The Coalition to Counter ISIS, for example, comprises 68 countries and institutions that have come together around core principles such as military cooperation, disrupting the flow of foreign recruits to and from Iraq and Syria, cutting off ISIS’ access to the international financial system, addressing humanitarian crises, and countering the ISIS brand. Such cooperation is critical to ISIS’ defeat.
Since September 2014, members of the coalition—including Australia, Bahrain, Belgium, Canada, Denmark, France, Jordan, the Netherlands, Saudi Arabia, Turkey, the United Arab Emirates, and the United Kingdom—have carried out over 19,000 air strikes against the group in Iraq and Syria. Other cooperative efforts include pooling of ammunition and providing advisers to Iraqi military components to strengthen their efforts in the theater of battle.
Blocking ISIS’ access to resources is key, since it has positioned itself as the wealthiest terrorist organization in history. By conservative estimates, between 2015 and 2016, ISIS had approximately $1.5 billion in annual revenue, largely from taxation and extortion, but also from oil and smuggling operations, the sale of antiquities, and foreign donations. In response, the