How Microsoft’s Bing Helps Maintain Beijing’s Great Firewall

In spring 2021, just before the 32nd anniversary of the Tiananmen Square massacre, users of Microsoft’s Bing search engine in the US and Europe noticed something odd. Bing had stopped displaying famous photographs of Tank Man—the lone protester who blocked an armored column during the pro-democracy demonstrations of 1989. “There are no results for ‘tank man,’ ” announced the search engine in response to search queries. “Check your spelling or try different keywords.”

Asked about the issue at the time, a Microsoft Corp. spokesperson blamed “accidental human error.” According to three people familiar with the matter, the full explanation, which has never been publicly revealed before now, was that Microsoft accidentally applied the blacklist it uses for the Chinese version of Bing to the entire world, providing an unintended glimpse of how it works with Beijing to give Chinese users a sanitized view of the internet.