President Donald Trump on Christmas Eve repeated his concerns over Big Tech censorship a day after he vetoed a defense-spending bill over Congress’s failure to remove liability protections for Silicon Valley’s social media companies.

“Twitter is going wild with their flags, trying hard to suppress even the truth. Just shows how dangerous they are, purposely stifling free speech. Very dangerous for our Country. Does Congress know that this is how Communism starts?” Trump said in a Twitter post on Thursday night.

“Cancel Culture at its worst. End Section 230!” he said.

Trump and his administration have repeatedly underscored the risks of unbalanced policing of user content on social media platforms, claiming that the companies are engaging in conduct that limits conservative viewpoints and stifles free speech. The president and the Justice Department have urged Congress to roll back legal protections under Section 230 of the 1996 Communications Decency Act for companies that have engaged in censoring or political conduct.

Section 230 largely exempts online platforms from liability for content posted by their users, although they can be held liable for content that violates anti-sex trafficking or intellectual property laws.

The law allows companies to block or screen content “in good faith” if they consider it “obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable.” The protections, however, weren’t intended to apply to services that act more like publishers than online platforms, outgoing Attorney General William Barr said in a speech in May.

Leading up to and after the November general election, Twitter ramped up its policing of posts by the president and other users over claims of voter fraud. In a Nov. 12 update, the social media company said it had applied labels, warnings, and other restrictions to about 300,000 posts from Oct. 27 to Nov. 11 for content that they classified as “disputed and potentially misleading.” This number represents about 0.2 percent of all U.S. election-related posts published in that time period.

A series of Trump’s posts that argued that there has been voter fraud have been labeled with: “This claim about election fraud is disputed.” For example, Twitter labeled Trump’s Nov. 22 post that stated: “In certain swing states, there were more votes than people who voted, and in big numbers. Does that not really matter? Stopping Poll Watchers, voting for unsuspecting people, fake ballots and so much more. Such egregious conduct. We will win!”

Following Dec. 14, the social media giant has been labeling some posts with “Election officials have certified Joe Biden as the winner of the U.S. Presidential election,” even though a number of legal challenges against 2020 election results—several that have reached the U.S. Supreme Court—have not been resolved.

On Wednesday, Trump carried through with his promise to block the defense-spending bill, the National Defense Authorization Act (NDAA), because it failed to make changes to section 230, among other reasons. He also characterized the bill as a “gift” to the Chinese Communist Party and Russia.

“Unfortunately, the Act fails to include critical national security measures, includes provisions that fail to respect our veterans and our military’s history, and contradicts efforts by my Administration to put America first in our national security and foreign policy actions,” he said in a Dec. 23 statement.

The DOJ has also been active in encouraging lawmakers to consider making amendments to what they describe as “outdated” law. They introduced a set of proposals earlier in the year that would curtail broad legal protections for online platforms in an effort to push tech companies to address illicit material while moderating content responsibly.

It also urged lawmakers to consider taking up proposals to update section 230 back in October when Twitter began suppressing a series of exposés by the New York Post about the alleged business dealings of Hunter Biden, son of Democratic presidential candidate Joe Biden.

“The events of recent days have made reform even more urgent,” Assistant Attorney General Stephen E. Boyd wrote in the letter (pdf) obtained by media outlets. “Today’s large online platforms hold tremendous power over the information and views available to the American people. It is therefore critical that they be honest and transparent with users about how they use that power. And when they are not, it is critical that they can be held accountable.”