Founded as a collective defense alliance in the early years of the Cold War era and then transforming itself by acquiring new missions during the U.S.-led unipolar period between 1991 and 2008, NATO is once again trying to redefine its core rationale amid growing geopolitical confrontations among key global actors, such as the U.S., China, Russia and the EU. This article mainly seeks to answer to what extent the resurgence of great power rivalries might pave the way for NATO’s transformation into a credible global security organization in the emerging century. Although the chasm between the U.S. and its European allies has continued to widen in recent years, cohesion among NATO members with respect to the emerging multipolar world order and how Russia and China should be handled is now more vital than ever to the persistence of NATO as a credible global security actor. NATO’s future will also be informed by how Russia and China view the existing liberal international order in general and NATO in particular. This article contends that NATO’s transformation in the coming years will be increasingly informed by the evolving dynamics of great power politics.