Twitter revealed on Monday that it had shut down 200,000 accounts that it claimed “originated in China,” over posts relating to the ongoing mass protests of workers and youth in Hong Kong. The purge is one of the largest in the history of the platform.

A post by the “Twitter Safety” department entitled “Information operations directed at Hong Kong” stated that it had removed the accounts, because they were part of a “coordinated state-backed operation… originating from within the People’s Republic of China (PRC).”

Facebook also announced that it had removed five profiles and three groups, after being alerted to “inauthentic behaviour” associated with “the operation” by Twitter.

The US social media giants have accused the banned accounts of having repeated the Chinese government’s denunciations of the mass popular demonstrations in Hong Kong.

Twitter took the unusual step of sharing hundreds of megabytes of data, including Tweets and other information from 936 banned accounts that are hostile to the Hong Kong protests.

While the World Socialist Web Site opposes Beijing’s denunciations of the Hong Kong protests, the censorship by Twitter and Facebook of Chinese accounts is in line with US foreign policy and the Trump administration’s mounting confrontation with China. The US is yet to intervene openly in the Hong Kong protest movement, but behind the scenes it is no doubt calculating whether it can exploit the protests for its own purposes.

The latest mass purge is the latest stage in a protracted campaign to censor social media, conducted in close coordination with US and other western intelligence agencies.

In the course of this campaign, that has spanned more than two years, pages and material critical of US-led wars and government policy have been systematically targeted for removal, or have been made less accessible as a result of changes to algorithms that determine the content that is most visible to users.

As in previous instances of social media censorship, Twitter’s assertions are opaque and entirely unsubstantiated.

Its statement on Monday claimed that some of the accounts had been banned because they had engaged in “spam” or because they were “fake.” The post, however, also said that the accounts had been targeted because they were “deliberately and specifically attempting to sow political discord in Hong Kong, including undermining the legitimacy and political positions of the protest movement on the ground.”

In other words, individuals and accounts have been blocked from the platform, for voicing political opinions. This establishes a precedent for the mass removal of accounts that express political views that run counter to those being promoted by Twitter and its backers in the US corporate and political establishment.

The limited information contained in Twitter’s post undermines the company’s claim that all, or even the majority of banned accounts were controlled by the Chinese state. The company stated: “As Twitter is blocked in PRC, many of these accounts accessed Twitter using VPNs.”

In other words, the banned accounts were subject to the same Chinese government restrictions as the entire Chinese population and had to use a VPN (virtual private network) to evade the block. This would tend to indicate that the individuals operating the accounts were not doing so in any official capacity.

Some of the banned accounts, moreover, had a lengthy history of sharing content that had nothing to do with politics, including posts about popular culture.

Some 236 of the accounts had more than 10,000 followers, while several had hundreds of thousands. This suggests that they had built up a substantial audience over a protracted period, contradicting Twitter’s claim that the targeted accounts were all part of a recently created “spammy network.”

The scale of Twitter’s purge raises the prospect that accounts from China are being summarily deleted. Prior to the 30th anniversary of the Tiananmen Square massacre in June, Twitter deleted hundreds of accounts, but subsequently apologised after it was revealed that most of the accounts were critical of the Chinese regime.

The latest censorship confirms that the social media giants are being transformed into censorship tools for US imperialism, deleting accounts that are critical of its actions or that do not conform to American foreign policy.

Last month, the platform suspended the account of Unity4J, an international network that defends Julian Assange. The accounts of other supporters of the WikiLeaks founder, who is being persecuted for exposing US war crimes, were also summarily removed.

Most of the accounts were only reinstated after weeks of public protest. No-one was provided with any explanation for the temporary deletion of their pages.

Facebook has also engaged in blatant political censorship. Last year, it temporarily removed the pages of popular Venezuelan-owned news site Telesur and Venezuela Analysis. The pages, which had hundreds of thousands of followers, were deleted on the basis of unsubstantiated accusations of violating “terms of use.”

The censorship occurred amid a stepped-up US-sponsored regime-change operation against the Venezuelan government, and was aimed at blacking out any exposure or criticism of the US moves.

Twitter’s statement on Monday signalled that a further crackdown is underway. “As we have said before, it is clear that information operations and coordinated inauthentic behavior will not cease… we are committed to understanding and combating how bad-faith actors use our services,” it wrote.

Twitter also announced on Monday that it would “not accept advertising from state-controlled news media entities.” The new policy is transparently directed against Chinese and Russian media. Twitter stated that the ban would not affect “taxpayer-funded entities, including independent public broadcasters,” such as the BBC, which toes the line of the British government.

The policy is in line with hysterical denunciations of Russian state-owned media, by senior figures within the US political establishment.

The popular RT news network has been particularly targeted. Its stories exposing social inequality and political corruption in the US, and content critical of Washington’s foreign policy, have been presented by the American intelligence agencies as an illegitimate attempt to “sow discord.”

The censorship measures employed by Twitter and Facebook have gone hand in hand with the promotion by both platforms of corporate media outlets such as the New York Times and the Washington Post .

At the same time, the social media giants freely allow the publicly-disclosed efforts of the US allies to disseminate government propaganda. Leaked documents have previously revealed heavily-funded attempts by the British military and intelligence agencies, along with the Israeli state, to “influence” social media.

The escalating drive to online censorship is being fuelled by the fears of the ruling classes internationally, over a growing upsurge of the working class, and mass opposition to war, inequality and dictatorship.

In their anti-democratic actions, Facebook and Twitter are following the lead of Google, which in 2017 introduced a new search engine algorithm aimed at reducing traffic to progressive, left-wing and anti-war websites. The World Socialist Web Site was among the hardest hit, with a 74 percent decrease in Google search referrals within months of the policy being implemented.