This chapter focuses on the history of United States-North Atlantic Treaty Organization (US-NATO) ties, giving particular attention to the origin of long-term challenges that have complicated the relationship and the role that NATO has played in pivotal national security challenges for the US. It explores stock of how NATO is perceived among the US public and policymakers. The chapter describes the role NATO plays in US national security strategy, especially when it comes to how policymakers perceive the external security environment. It provides an overview of the US role in debates about defense spending and NATO’s budget. The chapter discusses the most likely trajectory for relations between the US and NATO. The constructive role for the US makes sense because NATO remains an essential part of its national security strategy. In addition to structural trends abroad, significant changes in the domestic landscape are changing the nature of US international engagement, including the relationship with NATO.