When massive protests broke out in Hong Kong last year over a contentious extradition bill, part of a pattern of Chinese encroachment on the semiautonomous city, senior U.S. officials including President Trump and Secretary of State Mike Pompeo issued calls for security forces and Beijing to respect the rights of protesters and listen to their demands.

Less than a year later, with the world’s attention captured by images of U.S. authorities using tear gas, pepper spray and rubber bullets to crack down on protesters against racism and police brutality, China and other U.S. rivals have seized the opportunity to highlight U.S. domestic turbulence and accuse Washington of hewing to double standards.

Over the past week — as Americans flooded the streets of major cities in response to the death of George Floyd, a black man who died in police custody in Minneapolis last week after a white officer knelt on his neck for […]