(Thomas White/Reuters)

MARCO RUBIO says Twitter is acting as a censor for the Chinese government. It isn’t — at least not on purpose.

Accounts critical of China were suspended from the social media site this weekend, only days before the 30th anniversary of the Tiananmen Square crackdown. Some suggested Twitter had been complicit in the state’s systematic suppression of dissent, which swells annually around remembrances of the massacre. Others thought the state had tricked Twitter by mass-reporting activists, based both domestically and abroad, for the platform unwittingly to remove — an ominous development signaling China’s ability to export censorship.

These charges, including by the Florida Republican senator, were alarming. They were also, it appears, inaccurate. But that does not mean there isn’t a problem. Twitter has apologized and promised to restore users who were inadvertently removed in what it describes as a “routine action,” or one of the salvos against spammy and manipulative practices that purge 8 million to 10 million people from the platform every week. Twitter was, in other words, attempting to do something responsible. The trouble is, it also affected some of the people anti-manipulation efforts are supposed to empower.

The debacle reveals once more the challenges of large-scale content moderation in an age of imperfect algorithms. It has been suggested that the virtual private networks, or VPNs, that many in China use to vault the country’s infamous Great Firewall might have caused some of the confusion: VPNs can be a valuable tool for evading platforms’ policing, but treating them as a signal of inauthenticity in a country where dissidents rely on them can backfire. And that is only one way filters such as Twitter’s can fall short.

Fallibility is exactly why platforms employing machines for their police work must be so cautious. Human rights groups and other observers are understandably dubious after this weekend; Twitter cut off Chinese activists from each other and the world almost on the eve of the most fraught day in that nation’s calendar. That may have well have been a coincidence, but it was an awfully unfortunate one. An automatic Chinese-language cleanup far-reaching enough to scrub away well-known activists would have been risky at any time, depending on how it was carried out and with what level of review. It is riskier still so near to June 4. An investigation from Twitter on what went wrong, and why, would assuage concerns today and offer lessons for tomorrow.

China, with the help of ever-evolving technologies, is getting better and better at repressing its citizens. It is heartening that platforms such as Twitter refuse to participate in that repression, but they must do more. They must thoughtfully, and carefully, act against it.