U.S. President Barack Obama came into office determined to end a seemingly endless war on terrorism. Obama pledged to make his counterterrorism policies more nimble, more transparent, and more ethical than the ones pursued by the George W. Bush administration. Obama wanted to get away from the overreliance on force that characterized the Bush era, which led to the disastrous U.S. invasion of Iraq in 2003. That war, in turn, compromised the U.S. campaign against al Qaeda. During the past six-plus years, Obama has overseen an approach that relies on a combination of targeted killing, security assistance to military and intelligence forces in partner and allied countries, and intensive electronic surveillance. He has also initiated, although in a tentative way, a crucial effort to identify and address the underlying causes of terrorism. Overall, these steps amount to an improvement over the Bush years. But in many important ways, the relationship between Bush’s and Obama’s counterterrorism programs is marked by continuity as much as by change.
One important difference, however, is that whereas Bush’s approach was sometimes marred by an overly aggressive posture, Obama has sometimes erred too far in the other direction, seeming prone to idealism and wishful thinking. This has hampered his administration’s efforts to combat the terrorist threat: despite Obama’s laudable attempts to calibrate Washington’s response, the American people find themselves living in a world plagued with more terrorism than before Obama took office, not less. Civil war, sectarian tensions, and state failure in the Middle East and Africa ensure that Islamist terrorism will continue its spread in those regions—and most likely in the rest of the world as well. Most worrisome is the emergence in Iraq and Syria of the self-proclaimed Islamic State (also known as ISIS), a protean Salafi jihadist organization whose brutal violence, ability to capture and hold territory, significant financial resources, and impressive strategic acumen make it a threat unlike any other the United States has