Chinese state media announced the latest Internet censorship campaign on Wednesday, describing it as a “rectification” program that combines the efforts of China’s cyberspace agency, information technology ministry, public security officials, and market regulators.

The rectification campaign, in progress for two weeks before the government formally announced it, has reportedly blocked hundreds of websites and social media accounts. The regime accused targeted websites of “illegal and criminal actions,” including failure to protect the personal information of users.

“Several foreign media beyond Beijing’s control, such as the Washington Post and The Guardian, have not been accessible online since last weekend, adding to a list of blocked sites that includes Reuters,” Reuters reported on Wednesday.

The crackdown included new censorship orders for popular Chinese search engine provider Baidu:

The Chinese internet regulator’s Shanghai office said in a statement on Wednesday that it and the markets regulator’s Shanghai office summoned representatives from Baidu Inc and criticized the firm for unethical advertising using vulgar content or overly sensational titles. The authorities ordered the search engine operator to rectify its advertising business to eliminate such practices, according to the statement, which quoted a Baidu representative as saying the firm would make necessary changes.

Another banned foreign website, the Newsroom of New Zealand, found NBC News, the Toronto Star, the Huffington Post, and the Intercept among the other blockaded sites.

The Newsroom speculated it landed on the “rectification” ban list by discussing the 30th anniversary of the Tiananmen Square massacre, an event the Chinese Communist Party wishes to erase from history. Business Insider thought some of the other foreign websites may have been blocked for similar reasons.

“This frenzied activity could indicate that the authorities are accelerating their push to sever the link between Chinese citizens and any news source that falls outside of the influence of the Party,” Charlie Smith of Chinese censorship watchdog GreatFire.org told The Newsroom. The name of Smith’s site is a riff on the “Great Firewall of China,” the name given to Beijing’s increasingly aggressive efforts to segregate China from the global Internet.

Reuters quoted analysts who saw the “rectification” campaign as a combination of political censorship and more defensible Internet hygiene, noting that Chinese users are buffeted with a great deal of spam and pornography.

Most troubling is the apparent crackdown on “self-media,” a Chinese term for small independent news and commentary websites – in essence, blogs. Chinese officials have long accused self-media operators of spreading “misinformation.” A previous purge in November shuttered almost 10,000 independent news social media accounts.

Self-media science writer Shimin Fang told Reuters his social media accounts were shut down this week without explanation. He suspected it had something to do with his criticism of telecom giant Huawei, which the Chinese government is desperately trying to protect from blacklisting by the United States.

“The Chinese Internet winter is coming,” said Fang, borrowing an ominous phrase from the popular Game of Thrones fantasy series.