The United States in the Sahel

In the first year of the Biden administration, the United States has wound down elements of its military operations against ISIS, al-Qaeda, and certain affiliates – commonly referred to as the “war on terror” – notably completing the withdrawal of U.S. forces from Afghanistan and significantly reducing airstrikes in Somalia. At the same time, the administration continues to conduct occasional strikes, including in Syria and Somalia, and has left in place much of the legal, institutional, and physical infrastructure that underpin this decades-long conflict. A future president – or this one – therefore would have the necessary tools to once again unilaterally ramp up hostilities, just as prior administrations of both parties dramatically expanded the conflict by stretching the 2001 Authorization for Use of Military Force (2001 AUMF) to apply to a broad array of actors and locales. One region where this could happen is the Sahel, where limited U.S. operations continue, generally in support of partner forces, although it is unclear whether there is any direct threat of external attacks against the United States by the groups U.S. partners are fighting. Despite the lack of clarity regarding core U.S. national security interests, the pieces remain in place for an expansion of the war on terror in the Sahel should this or a future administration so decide.

A Brief History of the Ever Expanding AUMF

As detailed in the Crisis Group report, Overkill, the spread of the war on terror has for two decades been driven by the executive branch.

The 2001 AUMF authorizes the president to use force against those “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.” Although Congress clearly intended the authorization to apply to the perpetrators of the 9/11 attacks and those that harbored them, namely al-Qaeda and the Taliban, the executive branch has relied on creative interpretations to effectively sever that connection and to unilaterally stretch the 2001 AUMF.

Such interpretations have included the theory spawned by the executive branch during the George W. Bush and Barack 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. (Congress eventually endorsed the concept of associated forces in the National Defense Authorization Act for Fiscal Year 2012 (2012 NDAA), but did not speak to the executive’s assessment of which groups so qualify). Although the executive branch used the concept of “associated forces” early on in order to justify the detention of non-al-Qaeda, non-Taliban detainees at Guantanamo Bay, it later repurposed the concept in order to use lethal force against groups far removed Afghanistan’s battlefields such as Al Shabaab in Somalia.

The Obama administration innovated further when it concluded that the AUMF authorizes the use of force against the Islamic State even though the group split from al Qaeda and therefore does not appear to fit within the definition of…