This article studies the evolution of the United States’ post-colonial Hong Kong (HK) policy from liberalism to realism. The author considers factors influencing this policy and differences between the White House/ Department of State and Congress in their assessment of and reaction to developments in HK. In 1992, Congress passed the United States–Hong Kong Policy Act, which treated HK as a non-sovereign entity distinct from China, made the United States a quasi-guarantor of HK’s autonomy and provided a framework for the advancement of grand liberal strategy of the United States towards HK in pursuit of the promotion of Western-style democracy in this special administrative region of China. During the first 17 years following HK’s handover to China, the U.S. government paid little attention to the region, avoiding public criticism of the Chinese authorities over the slow pace of territory’s democratization, while some prominent anti-China hawks in Congress were unrestrained in such criticism. The 2014 protests in HK did not alter the U.S. government’s cautious approach to HK. The Obama administration probably hoped for gradual democratic reforms in HK. Washington’s policy towards HK made a dramatic turn in 2018 on the back of rapidly deteriorating U.S.–China relations after Donald Trump came to power. The Trump administration was disillusioned with the liberal agenda and was very eager to actively play the HK card against Beijing. The large-scale protests/riots in HK in 2019 challenging China’s sovereignty over the territory were publicly supported, and in fact encouraged by top officials in the Trump administration and prominent Congressmen. After Beijing imposed the National Security Law (NSL) on HK in June 2020, the anti-government movement was squashed. This prompted Trump to strip HK of certain privileges under the HK Policy Act. The NSL caused Washington to lose many of its allies in HK, its influence in the territory diminished and its ability to promote American democracy agenda was hampered. NSL signifies a final transition from American liberal strategy to realism vis-a-vis HK, which is now fully covered by the U.S. policy to contain China. Washington will likely reduce its economic exposure to HK and use deep-seated anti-Beijing attitudes of some Hongkongers to undermine stability of this vulnerable territory of China.