Cooperating with Iran to Combat ISIS in Iraq

Two conflicting trends characterize the recent evolution of the Islamic State in Iraq and Syria (ISIS). On one hand, the group has lost over 45 percent of its territorial gains in Iraq and about 20 percent of the areas it controlled in Syria. The number of active foreign fighters in those countries has also decreased considerably.  On the other hand, ISIS has demonstrated the ability to orchestrate an increasing number of high-casualty attacks in cities and capitals throughout the world including in Paris in November 2015, San Bernardino in December 2015, Brussels in March 2016, London in March and June 2017, and to many observers' surprise, in Tehran in June 2017. Former Central Intelligence Agency (CIA) Director John Brennan noted that ISIS' capability to conduct global terrorist attacks had not been disrupted despite its territorial losses....