Twitter escalated tensions with President Donald Trump on Friday, adding a warning to one of his tweets for the first time and saying he violated the platform’s rules by glorifying violence when he suggested protesters in Minneapolis could be shot.

Trump has been railing against the company since earlier this week, when it for the first time applied fact checks to two of his tweets. Those were about mail-in ballots.

The flap comes at a fraught moment for Twitter and social media more generally. Debate is heating up about when and how much these companies should police the content on their platforms as coronavirus misinformation swirls and the 2020 U.S. presidential election looms.

For Trump, the feud with Twitter serves as a convenient distraction from major challenges he faces heading into November, such as controlling a pandemic and dealing with soaring unemployment.

The Trump tweet that was flagged Friday came amid days of violent protests over the death of George Floyd, a handcuffed black man who pleaded for air as a white police officer kneeled on his neck.

“These THUGS are dishonoring the memory of George Floyd, and I won’t let that happen,” Trump tweeted about the protesters. “Just spoke to Governor Tim Walz and told him that the Military is with him all the way. Any difficulty and we will assume control but, when the looting starts, the shooting starts. Thank you!”

Twitter did not remove the tweet, saying it had determined it might be in the public interest to have it remain accessible. But the tweet was hidden so that a user looking at Trump’s timeline would have to click on the warning to see the original tweet. Hiding it also effectively demotes the tweet by limiting how users can retweet it and ensuring that Twitter algorithms don’t recommend it.

Twitter said Friday it posted the warning labels on Trump’s tweets “based on the historical context of the last line, its connection to violence, and the risk it could inspire similar actions today,” but left them up “given its relevance to ongoing matters of public importance.”

A tweet using the same language as Trump’s was later posted on the official White House Twitter account, and Twitter eventually put a warning on that too. It was also posted on Facebook, which hasn’t taken any visible action on it.

Twitter taking a harder line than Facebook on Trump’s posts likely has something to do with Twitter’s decision last year to stop taking political ads, said Melissa Ryan, CEO of consultancy group Card Strategies, which researches online disinformation and right-wing extremism.