Today’s 21st anniversary of the Tiananmen Square massacre has not passed without controversy.

This cartoon, published on Tuesday in the Southern Metropolis Daily was pulled from the newspaper’s website after it started attracting online interest. The image was part of a series commemorating International Children’s Day but it clearly references Tank Man, the lone protester who stood in front of a column of tanks, now the emblematic image of the massacre.

This is a brave move for the Guangdong-based newspaper, which has reputation for being one of the most independent news outlets in mainland China. However the decision to run the print edition and pull the online one has raised questions; was the cartoons publication a mistake — perhaps an overworked editor missed the underlying symbolism — or was the paper simply forced to pull the online version due to government pressure? So far, the Southern Metropolis Daily has declined to comment on the situation.

Elsewhere the authorities have kept tight control around the physical domains of Tiananmen Square and Beijing; on the geography-based social networking website foursquare.com users have staged online vigils, “checking in” to the virtual Tiananmen Square in a show of solidarity. In response, the Chinese government today blocked access to the website from mainland China. Around the world, protests have taken place in cities such as Hong Kong and Tokyo, where one of the original student demonstrators, Wu’er Kaixi, was arrested for trespassing on the Chinese Embassy. Wu’er, an activist of Uighur descent currently lives in exile in Taiwan.

In a strange twist, it was announced today that the June 4th diaries of China’s premier at the time, Li Peng, will be published this month. Secrecy still surrounds the decision to use the military to crush the student-led protests, and the Chinese government still refuses to publish verifiable figures for the number of injured or killed civilians during the protests. Although doubts have been cast on the book’s authenticity, the diaries are rumoured to provide an insight into senior officials thinking during the crisis and background into how government decisions were reached, including the deployment of martial force in the Square. In one of the passages, Li Peng is quoted as saying he will “sacrifice” his life in order to prevent another Cultural Revolution from occurring. If the book turns out to be genuine, it could be the government’s attempt to justify its actions 21 years ago.