Against the backdrop of worsening tensions across the Taiwan Strait, this Element analyzes the positions and policies vis-à-vis Taiwan of six major democratic US treaty allies-Japan, Australia, South Korea, the United Kingdom, France, Germany-and the European Union. Historically and today, these US partners have exercised far greater agency supporting Taiwan's international space and cross-Strait stability-in key instances even blazing early trails Washington would later follow-than the overwhelmingly US-centric academic and policy discourse generally suggests. Decades ago, each crafted an intentionally ambiguous official position regarding Taiwan's status that effectively granted subsequent political leaders considerable flexibility to operationalize their government's 'One China' policy and officially 'unofficial' relationship with Taiwan. Today, intensifying cross-Strait frictions ensure that US allies' policy choices will remain critical factors affecting the status quo's sustainability and democratic Taiwan's continued viability as an autonomous international actor. This title is also available as Open Access on Cambridge Core. Amid surging global concerns about cross-Strait peace and stability, this study analyses the agency of key US treaty allies.