Twenty years after al-Qaeda launched its most brazen attack on American civil society—or, as some of us conceived of it, on civilization itself—a strategic and historical exhaustion has overtaken American thinking about the War on Terror. The political class and the public have wearied of the moral and martial exertions involved in suppressing violent insurgencies and dispatching holy warriors across the lands of Islam. 

Despite the many differences—profound and cosmetic—between the Biden administration and its two immediate predecessors, it’s clear that all sought to pivot away from the Middle East. None attempted to justify a continued American presence in the region. Both parties have shown dwindling patience with the use of American military force and a marked timidity about exercising assertive leadership in the world. The old consensus about America’s role as upholder of global security—tenuous since the end of the Cold War—has collapsed.