The fundamental inquiry that motivates this thesis is: to illuminate in what way, and to what extent, NATO’s operations in Afghanistan have affected the Alliance. More specifically, how NATO has adapted to American initiatives of transformation in light of the war in Afghanistan, and the American paradigm of War on Terror. Transatlantic relations within NATO is my subject, and Afghanistan is my chosen case. The question I strive to answer is whether Afghanistan specifically, and the War on Terror in general, has wielded a dividing or unifying effect upon the Alliance. I do so by studying the political, organizational and military impact of its Afghan engagement on NATO. I analyze changes within the alliance in regard to these three dimensions, and the Alliance's process of transformation between 2001 and 2010. All in reference to the War on Terror as the US's ruling security paradigm and NATO's involvement in Afghanistan.