But the judge did not hold back on Thursday when she sentenced Stone to three years and four months in prison for lying to a congressional committee investigating Russian interference in the 2016 US election, obstruction of justice and witness tampering. Jackson said Stone showed "flagrant" disrespect for the proceedings.

The 65-year-old jurist, without mentioning Trump by name, called his attempts to influence the case "inappropriate" and said he did not sway her decision. Jackson also blasted Stone's behaviour during the proceedings, which included a social media post that looked like a gun's crosshairs over her head.

Jackson took aim at Attorney General William Barr, a Trump appointee, and other senior Justice Department officials for their decision to overrule prosecutors last week to seek a lighter sentence for the veteran Republican operative after Trump publicly complained about the case.

"I fear that you know less about the case ... than just about every other person in this courtroom," Jackson told prosecutor John Crabb, named to take over the case after his four colleagues quit it in protest.

Crabb apologised for "the confusion" the government caused and called the prosecution of Stone "righteous" even as Trump called it unfair. Crabb added that the department "is committed to enforcing the law without fear, favour or political influence." Democrats accused Trump and Barr of politicising the criminal justice system.

"Roger Stone will not be sentenced for who his friends are, or who his enemies are," Jackson said about the self-described "dirty trickster."

"The defendant lied about a matter of great national and international significance," the judge added.

Australian Associated Press