The article, which sets the stage for the present thematic issue of the journal, examines the evolving use of the terms pacing threat and pacing challenge in the context of US defense strategy, particularly in relation to China. It traces the origins of these phrases, noting that they have been used interchangeably and without a clear, codified definition. The authors provide working definitions for these terms, suggesting that a pacing challenge refers to an adversary that poses a long-term risk to US influence and power, while a pacing threat denotes a more immediate and consequential military threat. The article also discusses the concept of an acute threat, which is applied to more urgent and severe threats, such as Russia’s invasion of Ukraine. The article argues that clearly defining these terms is crucial for informing defense planning and policy. It concludes by highlighting the need for the United States to address China’s growing military, political, and economic capabilities, which constitute a significant pacing challenge, while also being prepared to counter any acute threats that may arise.