Introduction

In December 2011, the last U.S. troops left Iraq, completing the United States’ withdrawal from the Iraq war.¹ The Obama administration viewed the withdrawal as the culmination of one of its top campaign promises. Within three years the war in Iraq would snap back. The very Obama administration that heralded the withdrawal would commit American military power to fight ISIS² in Iraq, and then extend the war into Syria.

The counter-ISIS war accomplished much good. It destroyed ISIS's territorial caliphate that, at one point, ruled over almost 8 million people and encompassed an area about the size of Britain. Nestled in the heart of the Middle East, it was the launchpad from which ISIS carried out attacks in Europe and elsewhere.³

However, the war’s escalation raises serious questions regarding the sustainability and effectiveness of American counterterrorism strategy. On what basis did the United States justify the war? Did the United States return to preventive war logic while fighting the counter-ISIS campaign? Did ISIS directly threaten the United States? And has the war made the United States safer? Horror at ISIS's brutality has sidelined these questions.

This report examines the decision-making and impact of the counter-ISIS war as a historical case study seeking to answer these questions. It also draws lessons from the war for how the United States should develop a sustainable counterterrorism strategy that does not fuel endless war.

This report finds that the Obama administration invoked multiple rationales to justify the war. These rationales included preventive war logic; that is the view that war now is preferable to other options in order to prevent a future conflict in which a rival would pose a greater threat due to a growth in its capabilities. This was the very logic that led the United States into Iraq in 2003. However, the Obama administration’s public justification also included references to regional security, extraterritorial protection of Americans, and humanitarian rationales.

As the United States faced ISIS's brutality and interpreted it as posing a great threat to the United States’ regional security, humanitarian, and extraterritorial protection of Americans goals, decision makers increasingly perceived ISIS's existence—in any form—as fundamentally at odds with both international order and American values. This gave rise to an increased emphasis on American homeland security as it was tied to threats outside the homeland and encapsulated in a discourse of “common threat.” As a result it also fueled the rise of preventive war logic.

The preventive war logic adopted during the campaign has helped fuel America’s endless wars. The United States has failed to annihilate ISIS's resilient threat in Iraq and Syria, and the threat to the United States does not look substantially lower than it did before the war. There are renewed calls for a long-term U.S. military presence, not just in Iraq but in Syria as well. Meanwhile, the continued U.S. presence poses a substantial risk of fueling new conflicts. The Trump administration’s withdrawal from northeastern Syria has not ended the war’s endless character or its risks, having maintained a military presence in both Syria and Iraq.

This pessimistic vision is a predictable consequence of the adoption of preventive war logic, which often results in a shift to value-based analysis rather than cost-benefit analysis; an over-focus on reducing an enemy’s capabilities while underestimating the limits of military power to achieve a political solution; and the overstretch of American power.

The counter-ISIS war's escalation raises serious questions regarding the sustainability and effectiveness of American counterterrorism strategy.

Some strategic theorists have accepted the need for repeated wars as a way of suppressing terrorist threats. This strategy is known in Israel—where it is particularly prominent—as “mowing the grass” and holds little promise in the long run as a sustainable approach. While the counter-ISIS war achieved important ends at relatively low costs compared to previous wars, the potential for the lingering issues left unchecked to radically alter the assessment of the campaign’s success is significant. Nor is repetition of counter-ISIS wars likely to be sustainable as a strategy.

At the same time, the administration’s initiation of a counter-ISIS war reveals a challenge facing advocates of foreign policy restraint. The counter-ISIS war provides an example of a snapback problem where threats to regional security interests and to Americans abroad result in re-escalation, opening the door for the reemergence of preventive war logic.

Today, many politicians promise an end to these endless wars. Yet it is easy to overestimate the resilience of such promises due to an overemphasis on decision makers as unitary, rational actors with stable preferences. Instead, when confronted with terrorist threats, there are numerous pressures that encourage even restraint-oriented decision makers—as Obama was in many ways—to pursue re-escalation.

While there is evidence that the American public is reticent to engage in more wars, polling suggests the public remains fearful of terrorism and is willing to use airstrikes to wage war on terrorists.⁴ Indeed, in September 2014, Gallup showed 60 percent of Americans supporting strikes on ISIS in Iraq and Syria.⁵ Further, public support in the case of snapback is not restricted to support for airstrikes. An October 2014 CNN poll found that more than 70 percent of Americans would support the use of ground troops were ISIS to attack the U.S. embassy or other facilities in Baghdad.⁶

The danger of snapback can coexist alongside public or policymaker statements of desire for restraint. A September 2014 joint CBS and New York Times poll, for example, found that even as the United States expanded the counter-ISIS campaign, 46 percent of Americans believed that the United States was right to withdraw without leaving any troops in Iraq in 2011, but two-thirds favored sending military advisors to support Iraq in the counter-ISIS campaign.⁷

Policymakers do not respond to threats or public fears in a vacuum. Their public statements exist within a domestic political environment where opponents often aim to stoke fear and calls for greater action. For example, the Republican party and multiple Republican congressional candidates ran fearmongering ads and warned of fanciful ISIS threats to the homeland involving infiltration across the southern border and the use of Ebola.⁸ The 2014 midterm results suggest that simply ignoring such political hype as absurd resulted in the loss of public support for those who dismissed fear mongering without addressing fears.⁹

The danger of snapback can coexist alongside public or policymaker statements of desire for restraint.

In addition, shocking displays of terrorist violence can generate public and policymaker support for a return to war. In one September 2014 poll, 55 percent of those polled said ISIS's beheading of Americans held hostage made them personally angry.¹⁰ Because terrorism’s targeting of civilians violates entrenched values and norms of war, it often generates disgust and a related resolve on the part of states to not make concessions because the targeted population infers maximal ends from the extreme violence, as terrorism scholar Max Abrahms has argued.¹¹ The war on ISIS provides an example of this phenomenon where ISIS's extreme violence, including its murder of American hostages, led the Obama administration to see ISIS's objectives as not containable and requiring a broad military response.¹² ISIS's genocidal violence against Iraqi Yazidis likely had a similar effect. The administration was not wrong to view ISIS's objectives as tending towards the maximal, but even among radical terrorist groups, intent exists along a spectrum and the terrorist nature of any particular group does not eliminate the dangers of preventive war.

America is still fighting counterterrorism wars it began almost two decades ago. American military involvement in Iraq—going back to the Gulf War—has an even longer history. Ending these endless wars must be an American priority, but it will take more than calls for withdrawal to escape the snapback challenge.

The rest of this report is divided into five sections. This first section lays out the data used in this report and its limitations while also defining preventive war logic and the other rationales for war at work in the counter-ISIS campaign. The second section examines the justifications the Obama administration gave for the war, arguing that the Obama administration did embrace preventive war logic. However, it also argues that the preventive war logic grew out of other rationales for war that were more important in the decision to initiate the war. The third section examines what is known publicly about the threat ISIS posed to the American homeland, demonstrating that the justification for war regarding homeland security was preventive and not a direct self-defense or preemptive rationale. The fourth section recounts the negative consequences of the adoption of preventive war logic during the counter-ISIS campaign for American counterterrorism broadly and U.S. interests in Syria specifically. The fifth and concluding section draws lessons from the use of preventive war logic in the counter-ISIS campaign with regards to the challenging task of developing a sustainable counterterrorism strategy that does not fuel endless war.