The former Trump campaign chairman is charged with laundering millions from Vladimir Putin's allies in Ukraine.
The president has repeatedly called investigations into possible collusion between his campaign and Russia "a witch hunt."
Both men named in a 12-count indictment had significant roles in the Trump campaign.
They were indicted on 12 counts, including conspiracy to launder money.
Ranking the week’s 10 most disgraceful figures in the Trump administration.
A campaign adviser caught lying to the FBI about Russian "dirt" on Hillary Clinton is now cooperating with investigators.