Paul Manafort, campaign chairman for the Trump election campaign, has been jailed awaiting trial for witness tampering.
Mr Manafort was charged with witness tampering as part of special counsel Robert Mueller’s investigation into Russian interference in the US election.
US District Judge Amy Berman Jackson revoked his bail in Washington, sentencing him to jail after he pleaded not guilty.
“I have no appetite for this, but in the end, I cannot turn a blind eye,” she said.
“You’ve abused the trust placed in you.”
US President Donald Trump commented on the sentence, labelling it “tough” and “unfair”.
“Wow, what a tough sentence for Paul Manafort, who has represented Ronald Reagan, Bob Dole and many other top political people and campaigns,” he tweeted.
“Didn’t know Manafort was the head of the Mob. What about Comey and Crooked Hillary and all of the others? Very unfair!”
Mr Manafort is due to on trial in Washington in September and then faces another trial in Virginia on related charges.
He stepped down from managing the campaign when financial ties to pro-Russian Ukrainian groups emerged.