Force Without Authority explores why the United States' costliest military operations since Vietnam came up short and pushed Republican and Democratic leaders toward withdrawal and retrenchment. Covering the sweep of US armed interventions since the end of the Cold War, Jason Brownlee sets America's post-9/11 invasions in a thirty-five-year foreign-policy arc--from caution to bravado--and back. The al-Qaeda attacks suspended America's traditional aversion to high-risk military missions abroad. For the better part of a decade, presidents from both parties poured US troops into nation-building in Afghanistan and Iraq, only to return, in the 2010s, to a less hazardous and less ambitious program of eliminating enemies from a distance without reshaping politics on the ground. This same calculus pushed successive administrations toward diplomacy with America's most formidable foes. Critical and wide-sweeping, the book delivers a bracing audit of America's unipolar moment and a compelling case for statecraft over bluster.