Book excerpt: Airpower in the War against ISIS chronicles the planning and conduct of Operation Inherent Resolve by U.S. Central Command (CENTCOM) from August 2014 to mid-2018, with a principal focus on the contributions of U.S. Air Forces Central Command (AFCENT). Benjamin S. Lambeth contends that the war's costly and excessive duration resulted from CENTCOM's inaccurate assessment of the Islamic State in Iraq and Syria (ISIS), determining it was simply a resurrected Iraqi insurgency rather than recognizing it as the emerging proto-state that it actually was. This erroneous decision, Lambeth argues, saw the application of an inappropriate counterinsurgency strategy and use of rules of engagement that imposed needless restrictions on the most effective use of the precision air assets at CENTCOM's disposal. The author, through expert analysis of recent history, forcefully argues that CENTCOM erred badly by not using its ample air assets at the outset not merely for supporting Iraq's initially noncombat-ready ground troops but also in an independent and uncompromising strategic interdiction campaign against ISIS's most vital center-of-gravity targets in Syria from the effort's first moments onward.