Editorial: The Trump administration is right to say Hong Kong is no longer an autonomous region of China

The last time we flew out of Shanghai, China, it was 2015 and we stumbled across a sign hanging from the airport ceiling that seemed like an historical relic even then. It gave instructions — in English — for all travelers on domestic Chinese flights to head one direction and for all international travelers (which included those headed for Hong Kong and Taiwan) to head in the other direction. At the time, we smiled at the admission. The people of both places would appreciate that sign, but Beijing likes to think that both should be brought under its control.