A New York judge has fined Donald Trump for violating a gag order in his civil fraud trial.
Mr Trump was fined $5,000 (£4,100) by Judge Arthur Engoron on Friday.
The judge said in court that the former president had failed to remove an online post mocking a clerk at the court.
He also threatened Mr Trump with jail time, and demanded he take down the “untrue and disparaging” post made about the clerk earlier this month.
Judge Engoron said the post was deleted on social media, but remained on his website.
“Incendiary untruths can and have led to serious physical harm,” Judge Engoron said in court on Friday.
“I will now allow the defendant to explain why this should not end up with serious sanctions or I could possibly imprison him.”
Mr Trump’s lawyer, Christopher Kise, apologised on his client’s behalf and said it was an “inadvertent” mistake because while the post was deleted from social media, aides forgot to remove it from the campaign website.
Later in the day, Judge Engoron ruled that Mr Trump pay a fine given that “the violation was inadvertent, and given that it is a first time violation”.
“Make no mistake: future violations, whether intentional or unintentional, will subject the violator to far more severe sanctions, which may include, but are not limited to, steeper financial penalties, holding Donald Trump in contempt of court, and possibly imprisoning him,” Judge Engoron said in his ruling.
Mr Trump and several of his family members are on trial for fraud, falsification of business records, issuing false financial statements and conspiracy.
The non-jury, civil trial is focused on determining damages for the fraud that Judge Engoron has already determined Mr Trump committed by inflating his personal net worth to secure favourable loan agreements.
New York Attorney General Letiticia James, who brought the case, is seeking $250m (£205m) in penalties and severe restrictions for Mr Trump’s businesses.