Will the demonstrations in Hong Kong come to be seen as the end of a 30-year period, beginning with the Tiananmen Square massacre in 1989, of the American-Chinese economic engagement and entanglement christened “Chimerica” by historian Niall Ferguson?

Quite possibly, and without regard to what happens in Hong Kong. President Trump’s on-and-off tariff threats to China have shown his willingness to upend U.S.-China economic ties. Unlike his predecessors, he regards imports from China as harmful. In his view, they provide cheap clothes and toys to American consumers, but they also have destroyed more American manufacturing jobs than expected.