The U.S. determination  that Hong Kong is no longer autonomous from mainland China, under the Hong Kong Policy Act of 1992, will have significant implications for the city’s exporters and businesses.  Sensitive U.S. technologies could no longer be imported into Hong Kong, and the city’s exports might be hit with the same tariffs levied on Chinese trade.

But the act doesn’t cover the far more extensive role Hong Kong plays as China’s main point of access to global finance.  As of 2019, mainland Chinese banks held 8,816 trillion Hong Kong dollars ($1.137 trillion) in assets in the semiautonomous city, an amount that has risen 373% in the last decade…. China’s banks do much of their international business, mostly conducted in U.S. dollars, from Hong Kong. With Shanghai inside China’s walled garden of capital controls, there is no obvious replacement.

While the U.S. doesn’t directly control Hong Kong’s status as a financial center, Washington has demonstrated its extensive reach over the dollar system, with penalties against Korean, French and Lebanese financiers for dealing with sanctioned parties. The U.S. recently threatened Iraq’s access to the New York Federal Reserve, demonstrating a growing willingness to use financial infrastructure as a tool of foreign policy.  Even though the U.S. can’t legislate Hong Kong’s ability to support Chinese banks out of existence, the role of an international funding hub is greatly reduced if your counterparties are too fearful to do business with you.

Putting the ability of Chinese banks to conduct dollar-denominated activities at risk would be deleterious to China’s ability to operate financially overseas, posing a challenge for the largely dollar-denominated Belt and Road global infrastructure initiative. It would also put the more financially fragile parts of the country, like its debt-laden property developers, under strain.  China’s hope to develop yuan into an influential currency also centers on Hong Kong’s remaining a viable global financial center—more than 70% of international trade in the yuan is done in the city.

Excerpts from Mike Bird, How the US Could Really Hurt China, WSJ, May 290, 2020