Executive Summary

In the aftermath of the 9/11 attacks, the United States embarked upon multiple counterterrorism wars embedded within a larger frame of a global war on terror. More than two decades on, these wars seem endless. In particular, America’s war in Yemen against Al-Qaeda in the Arabian Peninsula (AQAP) and later, the fight against the Islamic State in Yemen has taken on an endless character. The United States has conducted counterterrorism strikes in Yemen for more than a decade.

Yet many continue to deny that “endless war” has meaning. Despite such denial, the United States’ war in Yemen has trapped it in a deteriorating situation that requires recognition and naming. The U.S. commitment to eliminating a terrorist threat that is already quite degraded exacerbates the larger crisis in Yemen, risks escalation, and militarizes American politics. Continuing the counterterrorism war while denying its endlessness and the unachievable character of the objective of defeating AQAP constrains American strategic thinking.

Some argue that the United States should abandon the binary of a decisive victory over or defeat at the hands of AQAP, and instead establish a framework of “sustainable counterterrorism” that includes open-ended military deployments, and constant monitoring tied to the use of air strikes to disrupt threats.

The binary of decisive victory or defeat is dangerous and part of how the war in Yemen became endless. However, the war’s history also reveals the dangers of adopting a framework of sustainable counterterrorism. Endlessness in Yemen has not been produced only by the adoption of unlimited objectives of defeating AQAP, but also by the failure to clearly specify and analyze the achievability of limited objectives that seek aims short of AQAP’s total defeat. Abandoning the mirage of defeating AQAP should not mean abandoning strategic thinking regarding ends short of decisive victory.

Rather than embracing endlessness under the name “sustainable counterterrorism” or chasing the mirage that the United States can defeat AQAP, the United States should build a full policy platform to end its endless wars. It is possible that there will be situations where the American people determine that military action is needed, but those decisions should be made with an eye to how such wars will end. Sustainable counterterrorism—insofar as it retains an open-ended state of war—prevents the strategic thinking that the project requires.

Key Findings

• The American counterterrorism war in Yemen has taken on an endless character in which the United States pursues objectives it cannot achieve. Yet, at the same time, the United States is not at risk of decisively losing the war by being defeated or denied access to the battlefield.
  • The 2001 Authorization for the Use of Military Force ensures that the state of war persists even when strikes are paused.
  • The history of pausing and resuming strikes in Yemen warns against interpreting a prolonged pause as ending the war.
• Unclear and shifting objectives contribute to the counterterrorism war’s endless character.
  • The war in Yemen was initially covert, preventing public evaluation of its justification and objectives.
  • The United States alternated between limited objectives of degrading or disrupting AQAP’s capabilities and unlimited objectives of destroying the group.
  • The United States rarely stated its limited objectives in measurable, positive terms. It instead presented objectives other than the destruction of AQAP as gerunds or processes without providing details regarding the conditions under which the objective would be achieved.
  • Substantial escalations and de-escalations in the pace of strikes have occurred without public explanation, making it difficult to evaluate the current state of the war and how tactics relate to strategic ends.
• The decision to rhetorically commit to the unlimited objective of destroying AQAP contributed to the war’s endless character.
  • Unlimited objectives may not be coherent when it comes to movements and decentralized non-state organizations.
  • AQAP and jihadism more broadly on the Arabian Peninsula are characterized by a long history of activity, ties to elites and local politics, and decentralization that make their destruction or defeat difficult and likely impossible.
  • Socio-economic conditions in Yemen make it difficult to eliminate AQAP over the long term.
  • Yemen’s internationalized civil war means the kind of deployment necessary to eliminate AQAP would likely escalate regional conflicts.
• Some limited objectives in Yemen may be achievable, but the United States has failed to analyze them in a way that would enable effective war termination planning.
  • The United States has demonstrated its ability to successfully kill key targets and to assist partners in denying AQAP territory. It has also arguably degraded AQAP’s external attack capabilities.
  • Maintaining the unlimited objective of destroying AQAP, even as pure rhetoric, obscures potential tradeoffs between limited objectives by presenting a mirage of a future in which the destruction of AQAP resolves all strategic tensions.
  • Beguiled by the unlimited objective, the United States has not fully assessed the potential that apparent successes regarding limited objectives may not be sustainable or are the result of factors other than U.S. military action.
• The emerging framework of “sustainable counterterrorism” risks institutionalizing endless war rather than providing an exit. It tends to presume that unexpected events will improve conditions while underplaying the risk that they will result in sudden escalations.
  • Sustainable counterterrorism fails to address the hole in American doctrine and theory when it comes to strategic ends to war other than decisive victory or defeat. In eliding the question of ends, sustainable counterterrorism can maintain unlimited objectives but in a more hidden fashion.
  • Sustainable counterterrorism mirrors the logic of “mowing the grass,” replacing strategic thinking with a focus on tactics that are easily overwhelmed by shifts in systemic risk. This approach risks fueling preventive war logic.
  • Sustainable counterterrorism’s emphasis on enabling partners risks over-identifying with them and losing the ability to exert pressure for needed governance reforms.
• AQAP’s threat to the United States is limited. The war has been conducted under conditions of extreme asymmetry of capabilities and violence.
  • AQAP has failed to mount a successful campaign of repeated attacks in the United States. Over almost two decades, al-Qaeda in Yemen has carried out and directed at most two attacks in the United States, killing three people.
  • Separated from the United States by oceans and about 8,000 miles, and unable to expand territory over the long term in Yemen itself, AQAP’s violence against the U.S. homeland is restricted to occasional raiding.
  • AQAP also struggles to target American forces in Yemen due to the United States’ use of drones and partner forces to remove American soldiers from the battlefield and insulate them from risk.
  • In contrast, the United States has killed more than 1,300 people in Yemen, demonstrating its ability to access the battlefield.
• Despite these limitations, AQAP demonstrated an ability to conduct significant raids on the U.S. homeland, and in the absence of military action, there is a reasonable case it would have carried out a campaign of repeated attacks. As a result, the U.S. decision to wage war in Yemen was made in a starker strategic context, regarding homeland security, than the decision to wage war against ISIS.
  • In 2009, AQAP almost brought down an airliner, which would have killed hundreds of people. AQAP followed its 2009 attack with two further plots targeting U.S. aviation.
  • U.S. government statements regarding the threat from AQAP portrayed it as posing credible, specific, and direct threats to the U.S. homeland while statements regarding ISIS portrayed it as a potential threat that might grow rather than an already existing one.
• The threat of AQAP and other foreign terrorist organization-directed attacks on the U.S. homeland has declined since the 2009-2012 period. Today, AQAP relies primarily upon its ability to inspire and advise potential attackers via the Internet. The degraded and decentralized threat raises doubts about the effectiveness and legitimacy of war as a response.
  • Government assessments and administration statements from 2009-2012 emphasized direct, existing, and credible threats to the United States.
  • More recent statements discuss potential threats and suggest a decline in capability.
  • The ability of potential attackers to travel to Yemen, receive material aid, and then enter the United States collapsed as a result of Yemen’s civil war.
  • AQAP’s recent propaganda has deemphasized the importance of travel to Yemen (an important step for directed attacks) in favor of inspiring attackers, who often act alone and lack material ties to the group.
• In order to end its endless war in Yemen, the United States must commit to clarifying its objectives while expanding transparency regarding the war AND abandon the objective of destroying AQAP or al-Qaeda more broadly.
  • A focus on clarifying the objectives and conduct of the war risks diverting needed critiques of whether the stated objectives are coherent and achievable to begin with.
  • An agenda that improves transparency without ensuring that U.S. objectives are achievable is likely to collapse over the long term.
  • Abandoning the unlimited objective of defeating AQAP without clarifying the United States’ other objectives risks generating an endless series of wars for shifting purposes.
• To sustainably end its counterterrorism war, the United States should further develop its planning for war termination and expand its set of non-militarized tools for addressing the variety of crises in Yemen.
  • Even restraint-oriented policymakers cannot be trusted to refrain from re-escalating the war in times of crisis, making efforts to address systemic sources of risk essential.
  • The collapse of the Yemeni government and fragmentation of Yemeni politics poses a major challenge to efforts to end the U.S. war and increases the risk of re-escalation and/or a renewed AQAP threat.
  • Due to its prior actions and ongoing relationships in the region, the United States cannot avoid responsibility for conditions in Yemen. Attempts to simply wash its hands of the country, viewing Yemeni suffering as acceptable or even beneficial in strategic terms, will likely fuel anti-American views.
• Continuing the state of war in Yemen is not low risk.
  • The U.S. strike on Islamic Revolutionary Guard Corps (IRGC) personnel in Yemen in 2020 illustrates the potential for U.S. action to become intertwined with other conflicts and escalate.
  • Continuing an endless state of war warps American politics, setting the United States up as a dominating power over Yemenis and militarizing domestic American politics—even in the absence of ongoing strikes.
  • The counterterrorism war in Yemen holds severe risks for American democracy and the moral underpinnings of American warfare precisely because of the radical asymmetry between the violence the U.S. carries out or is capable of carrying out in Yemen, and the violence AQAP is capable of carrying out against Americans.
• The United States should develop a full policy platform to end its endless counterterrorism war in Yemen. This should include:
  • Repealing the 2001 AUMF.
  • Strict oversight of counterterrorism operations.
  • A thorough, public review of U.S. strikes and objectives in the war in Yemen.
  • A public, detailed assessment of AQAP’s structure and threat.
  • A presidential speech and strategy document addressing the history of the U.S. war and abandoning unlimited objectives while explaining how any retained limited objectives can be achieved.
  • Efforts to improve American war termination planning and capabilities to respond to the multiple socio-economic, humanitarian, and political crises facing Yemenis.