The new red scare on American campuses

EARLY LAST autumn Alex and Victor, two students from mainland China, sat in the back row of a packed auditorium at Columbia Law School, in New York. They were there for a talk by Joshua Wong, thrice-jailed young hero of the Hong Kong democracy movement, which the two students support. They applauded enthusiastically; they also wore blue face masks.

The masks were in part symbols of solidarity with Mr Wong’s fellow protesters half a world away. But they were also a way of hiding their identities from face-recognition systems in China that might be scanning pictures of the audience, and from Chinese students in the hall less in tune with Mr Wong’s message—such as the ones who sang the national anthem of the People’s Republic in response to the talk. Their names are not, in fact, Alex and Victor; they asked The Economist to give them pseudonyms and not to say where in China they came from. As they talked, other Chinese students quietly observed them, national flags in hand.