Twitter has taken action over a tweet from US President Donald Trump in which he threatened to use "serious force" against protesters in Washington, saying it broke rules about abusive content.
The move on Tuesday appeared to be the first by Twitter against Mr Trump for an "abusive" tweet.
It is the latest clash in a growing dispute, the platform has recently labelled other tweets by him as misleading and in breach of its standards against promoting violence.
"There will never be an Autonomous Zone in Washington DC as long as I'm your President," Mr Trump tweeted.
"If they try they will be met with serious force!"
The action by Twitter requires users to click through to read the tweet, with a tag on the message saying that it "violated the Twitter rules about abusive behaviour", but would still be accessible "in the public's interest".
Mr Trump's tweet referred to the police-free district created by protesters in Seattle, Washington state, two weeks ago, which sparked outrage among conservatives.
Twitter's move intensified the battle between the White House and social media companies, which Mr Trump has accused of bias against conservatives, despite his own large following.
He has already signed an executive order that could lead to more government regulation of social media companies, despite doubts about its legality.
The Trump administration has also indicated that it wants to overhaul a law that gives platforms protection from content posted by others.
The reform which could open the floodgates to litigation.
Twitter said it acted on Tuesday because the tweet breached its policy against abusive behavior with "a threat of harm against an identifiable group."
In dealing with world leaders it mainly labels posts to be in breach, which limits its reach and prevents others from liking or retweeting it, but leaves them available if they relate to "ongoing matters of public importance".
The new, aggressive stand by Twitter against the president is in contrast with Facebook, which has maintained a largely hands-off policy despite pressure from activists to curb inflammatory content.
Facebook did remove a Trump advertisement last week that contained a symbol used in Nazi Germany for political prisoners, saying it breached the platform's policy against "organised hate".
