Argument

An expert's point of view on a current event.

Only Congress Can End Washington’s Endless Wars

The war on terror is a constitutional aberration. The U.S. legislature must reclaim its war powers from an overempowered executive branch.

By , senior advisor in the U.S. program at the International Crisis Group.
A ground crew guids a U.S. Air Force MQ-1B Predator unmanned aerial vehicle at an air base in the Persian Gulf region on Jan. 7, 2016.
A ground crew guids a U.S. Air Force MQ-1B Predator unmanned aerial vehicle at an air base in the Persian Gulf region on Jan. 7, 2016. John Moore/Getty Images

Oct. 7 marks the 20th anniversary of the U.S. invasion of Afghanistan. After two decades of the “war on terror,” the United States could be reaching an inflection point. In his recent speech before the United Nations General Assembly, U.S. President Joe Biden spoke of “[closing] this period of relentless war” and opening “a new era of relentless diplomacy.” U.S. forces have withdrawn from Afghanistan. The White House has also paused most airstrikes outside Syria, Iraq, and Afghanistan while the National Security Council coordinates a review of the policy framework for U.S. direct action operations—those that involve kill or capture.

A bipartisan coalition in Congress is demonstrating renewed interest in repealing and reforming authorizations for the use of force, including the 2001 Authorization for Use of Military Force (known in legal circles as the 2001 AUMF), which has been the legal foundation for the war on terror and which turned 20 last month. There could hardly be a better moment for the Biden administration and Congress to take stock of whether two decades of fighting in countries from Niger to the Philippines has made the United States or the wider world safer and whether, and to what extent, military force remains a necessary counterterrorism tool.

Yet the Biden administration appears focused solely on how to conduct the conflict rather than on more fundamental questions like whether to continue waging war or against whom. At the same time the administration speaks of “ending endless wars,” it continues discussing future “over-the-horizon” counterterrorism operations in Afghanistan and elsewhere. Indeed on Oct. 6, the Department of Justice told the U.S. Supreme Court that notwithstanding the “withdrawal of troops from Afghanistan,” the United States continues to be “engaged in hostilities” against al Qaeda. Nor has the executive branch been under significant pressure to fundamentally adjust its course.

Oct. 7 marks the 20th anniversary of the U.S. invasion of Afghanistan. After two decades of the “war on terror,” the United States could be reaching an inflection point. In his recent speech before the United Nations General Assembly, U.S. President Joe Biden spoke of “[closing] this period of relentless war” and opening “a new era of relentless diplomacy.” U.S. forces have withdrawn from Afghanistan. The White House has also paused most airstrikes outside Syria, Iraq, and Afghanistan while the National Security Council coordinates a review of the policy framework for U.S. direct action operations—those that involve kill or capture.

A bipartisan coalition in Congress is demonstrating renewed interest in repealing and reforming authorizations for the use of force, including the 2001 Authorization for Use of Military Force (known in legal circles as the 2001 AUMF), which has been the legal foundation for the war on terror and which turned 20 last month. There could hardly be a better moment for the Biden administration and Congress to take stock of whether two decades of fighting in countries from Niger to the Philippines has made the United States or the wider world safer and whether, and to what extent, military force remains a necessary counterterrorism tool.

Yet the Biden administration appears focused solely on how to conduct the conflict rather than on more fundamental questions like whether to continue waging war or against whom. At the same time the administration speaks of “ending endless wars,” it continues discussing future “over-the-horizon” counterterrorism operations in Afghanistan and elsewhere. Indeed on Oct. 6, the Department of Justice told the U.S. Supreme Court that notwithstanding the “withdrawal of troops from Afghanistan,” the United States continues to be “engaged in hostilities” against al Qaeda. Nor has the executive branch been under significant pressure to fundamentally adjust its course.

For the past 20 years, Congress has left the executive branch largely to its own devices to demarcate the legal and policy bounds of the war on terror, often in secret. Such a state of affairs is a constitutional aberration. The declare war clause and other provisions of the U.S. Constitution afford Congress, not the president, the lion’s share of power to decide against whom and where the United States is at war. But the combination of the 2001 AUMF’s broad wording, interpretive leaps by the executive branch, and congressional acquiescence have together enabled an end-run around constitutional design—creating a system in which the president and his advisors determine where and against whom to wage the war on terror.

Unless Congress reclaims its constitutional prerogatives with respect to war and peace, the executive branch could well continue the war on terror for another 20 years in another dozen countries without a fundamental reassessment of whether the United States should be at war at all.


Starting with the George W. Bush administration, the U.S. government’s executive branch has driven the war’s expansion. This growth has occurred through both top-down decisions in Washington and bottom-up decisions on the battlefield. Legal innovation by executive branch lawyers, particularly in their interpretations of the 2001 AUMF, played a critical role in facilitating the spread of U.S. military counterterrorism action.

The 2001 AUMF authorizes the president to use force against the “nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons.” But while Congress clearly intended the authorization to apply to actors with a connection to the 9/11 attacks, the executive branch has relied on creative interpretations to break that link.

Such interpretations have included the theory spawned by the executive branch during the George W. Bush and Obama administrations that the 2001 AUMF authorizes force against “associated forces” of al Qaeda—an elastic term that does not appear in the statute itself and has come to include groups far afield from Afghanistan’s battlefields. (Congress eventually endorsed the concept of associated forces.) Another such innovation was the Obama administration’s conclusion that the AUMF allows the use of force against the Islamic State even though it long ago split from al Qaeda.

The Trump administration, in turn, used these theories to sweep new “associated forces,” such as al Qaeda in the Islamic Maghreb and Islamic State affiliates in Yemen and Somalia, into the 2001 war authorization’s scope. A close cousin of mission creep, this “law creep” has facilitated the war on terror’s spread to new groups and new countries, sometimes even before Congress is aware it happened.

At the same time, U.S. special operations forces deployed on what are described as “advise, assist, and accompany” operations in a number of African countries have quietly expanded the war on terror’s scope from the ground up. Without consulting widely in Washington, these forces engage in ground combat and call in airstrikes, often under the rubric of self-defense or collective self-defense of local partner forces.

Whatever these operations’ policy merits, legal authority for these hostilities has often been murky. Executive branch officials are loath to second-guess claims of self-defense by forces in the field. Therefore, the executive branch has sometimes, as with al-Shabab in Somalia, adopted a “shoot first and apply the AUMF later” approach, whereby legally questionable combat operations, including airstrikes, are retroactively shoehorned into the 2001 AUMF.

As the war has grown, the executive branch has tried to manage the fallout through the imposition of policy safeguards. The Presidential Policy Guidance developed by the Obama administration was intended to coordinate and rationalize decision-making and create protections for innocent civilians who might be caught in the war’s crossfire, at least in countries away from the hot battlefields of Afghanistan, Iraq, and Syria.

The successor framework created by the Trump administration watered down the protections but did some of the same work. Tinkering with these frameworks, as the Biden administration is doing now, will not help answer fundamental questions raised by the continuation of a 20-year war. Indeed, unless this tinkering is joined to a deeper inquiry into the war’s costs and benefits, it will only further habituate policymakers to the use of military force as a primary counterterrorism instrument.

It is time for the legislative branch to reclaim its role with respect to matters of war and peace.

Congress needs to step in. It is time for the legislative branch to reclaim its role with respect to matters of war and peace. Reform of the 2001 AUMF would be the ideal vehicle to accomplish this.

By tailoring the new statute so it specifies where and against whom the use of force is authorized, Congress can raise questions about the war’s utility that desperately need a public airing. By removing the executive branch’s authority to add “associated forces” at will and otherwise read flexibility into the statute, it can spell the end of “law creep.” And by inserting a requirement that the conflict be reauthorized after two or three years, it can help ensure the war does not proceed for another two decades on autopilot.

The Biden administration should welcome such a move. It should explain to Congress and the public the nature of the evolving terrorist threat facing the United States today and its rationale for why military action is needed to address this threat. It should be careful in differentiating Islamist militants with local goals from those groups that possess both the intent and capabilities to attack the United States. Not every terrorist threat is a threat to the United States.

The tragic killing of civilians, including seven children, by the United States in a drone strike in Kabul on Aug. 29 is a reminder of the war on terror’s high human cost. Looking past jargon like “precision strike,” “reasonable certainty,” “collateral damage,” “over-the-horizon,” and “imminent threat,” the reality is the war’s continuation—if only by airstrikes and special operations forces—will inevitably result in further tragedies.

After 20 years, it is long past time for the White House, Congress, and the American public to reckon with whether this continued killing is worth it.

Brian Finucane is senior advisor in the U.S. program at the International Crisis Group. Prior to joining Crisis Group in 2021, he served as an attorney advisor in the Office of the Legal Advisor at the U.S. State Department. Twitter: @BCFinucane

Join the Conversation

Commenting on this and other recent articles is just one benefit of a Foreign Policy subscription.

Already a subscriber? .

Join the Conversation

Join the conversation on this and other recent Foreign Policy articles when you subscribe now.

Not your account?

Join the Conversation

Please follow our comment guidelines, stay on topic, and be civil, courteous, and respectful of others’ beliefs. Comments are closed automatically seven days after articles are published.

You are commenting as .

More from Foreign Policy

The Taliban delegation leaves the hotel after meeting with representatives of Russia, China, the United States, Pakistan, Afghanistan, and Qatar in Moscow on March 19.

China and the Taliban Begin Their Romance

Beijing has its eyes set on using Afghanistan as a strategic corridor once U.S. troops are out of the way.

An Afghan security member pours gasoline over a pile of seized drugs and alcoholic drinks

The Taliban Are Breaking Bad

Meth is even more profitable than heroin—and is turbocharging the insurgency.

Sviatlana Tsikhanouskaya addresses the U.N. Security Council from her office in Vilnius, Lithuania, on Sept. 4, 2020.

Belarus’s Unlikely New Leader

Sviatlana Tsikhanouskaya didn’t set out to challenge a brutal dictatorship.

Taliban spokesperson Zabihullah Mujahid

What the Taliban Takeover Means for India

Kabul’s swift collapse leaves New Delhi with significant security concerns.