This post has been updated and changed in the wake of comments from a LinkedIn spokesperson.

Every year in the weeks before and after June 4—the anniversary of the 1989 Tiananmen Square massacre—the Chinese government does two things: It “disappears” possible dissidents (paywall) and it blocks foreign online media to some degree. This year, the 25th anniversary of Tiananmen, was particularly intense on both scores.

But you wouldn’t know that from looking at LinkedIn in China, where the professional networking site launched a few months ago. Or, for that matter, outside the country. LinkedIn’s users both inside and outside of mainland China have reported that posts containing references to Tiananmen have been blocked. In emails to those users, LinkedIn’s management says this is due to “specific requirements within China to block certain content.” Here’s a look at an email received by Charles Mok, a Hong Kong legislator:

Apparently, LinkedIn was responding to new Chinese government policy. “These requirements have just recently gone into effect,” Deepa Sapatnekar, a LinkedIn spokeswoman, told Sinosphere.

What’s unclear, though, is why LinkedIn would enforce Chinese government censorship rules in Hong Kong. Though territorially part of the People’s Republic since 1997, Hong Kong is governed under the “one country, two systems” policy that allows protection of freedom of speech, press and publication guaranteed under Hong Kong law. However, attacks on Hong Kong press freedom have grown more and more frequent of late (in some cases, literally).

Update: A LinkedIn spokesperson responded to our request for comment, saying that the company sent a mistaken notification advising a small number of users in Hong Kong that their Tiananmen Square-related content was blocked, but that LinkedIn did not actually block content outside of mainland China (meaning Hong Kong LinkedIn is uncensored).

Another person to encounter LinkedIn’s censorship was Helen Couchman, an artist and longtime Beijing resident who moved to Britain in February 2013, according to the China Spectator. Couchman said that LinkedIn deleted her post linking to an article about the Chinese authorities’ detention of Guo Jian, a Chinese-Australian artist and friend of Couchman’s. (She shared the same article on Facebook and Twitter, where her posts are still available.) She subsequently tweeted her dismay at LinkedIn:

Fergus Ryan, a China-based reporter for China Spectator, received the same response from LinkedIn after he posted links about Guo Jian to his personal LinkedIn account.

Couchman’s LinkedIn account appears to be hosted on the mainland China site, cn.linkedin.com, which might explain why her posts fell under its censorship.

Of course, LinkedIn wouldn’t be the first Western tech company to struggle with the Chinese government’s censorship demands. Google famously shut down its mainland search engine in 2010, after wrestling with the government’s censorships and user privacy demands. More recently, Microsoft’s Bing has been accused of censoring more content than even Chinese companies—presumably in an effort to play it safe—including content outside mainland China. As the lone Western social media platform allowed in China, LinkedIn likely has similar anxieties; Twitter and Facebook were blocked around the time of the Jasmine revolution in February 2011, as it became clear how effective these platforms were for organizing protest.

Update and changes (June 4, 2014, 1:50 p.m.): This piece has been updated to include the comments of a LinkedIn spokesperson. The headline and several phrases have also been changed to reflect that LinkedIn’s blocking of Tiananmen-related content appears to apply only in mainland China.