The FBI has arrested two alleged agents for the Chinese government accused of working to harass and silence its critics in the US. The Justice Department also charged 34 officers of China’s national police, all of whom are believed to live in China, with related offenses. The revelations threaten to pitch already sour US-China relations into further crisis, and had the immediate effect of hardening bipartisan suspicion about Beijing on Capitol Hill in a way that will have serious diplomatic implications.