Twitter said Wednesday it has locked President Donald Trump’s account for 12 hours, and warned for the first time that it may suspend him permanently.

The temporary lock reflects Trump’s violation of the Twitter rules, the company said.

“We have required the removal of three @realDonaldTrump Tweets that were posted earlier today for repeated and severe violations of our Civic Integrity Policy,” Twitter said.

“This means that the account of @realDonaldTrump will be locked for 12 hours following the removal of these Tweets.

If the Tweets are not removed, the account will remain locked.”Twitter added that “future violations… will result in permanent suspension of the @realDonaldTrump account.”

The announcement marks a major escalation by Twitter against Trump’s account and responds to calls by civil rights groups for Trump to be banned from the platform.