US President Donald Trump has signed an executive order aimed at removing some of the legal protections given to social media platforms.
It gives regulators the power to pursue legal actions against firms such as Facebook and Twitter for the way they police content on their platforms.
President Trump accused social media platforms of having "unchecked power" while signing the order.
The order is expected to face legal challenges.
Legal experts says the US Congress or the court system must be involved to change the current legal understanding of protections for these platforms.
Mr Trump has regularly accused social media platforms of stifling or censoring conservative voices.
On Wednesday, Mr Trump accused Twitter of election interference, after it added fact-check links to two of his tweets.
On Thursday, Twitter added "get the facts about Covid-19" tags to two tweets from a Chinese government spokesman who claimed the coronavirus had originated in the US.