Manafort's detention order at a U.S. District Court hearing in Washington came a week after he was charged in a new indictment filed by Mueller. The indictment accuses Manafort and a Russian associate, Konstantin Kilimnik, of conspiring to influence the possible testimony of two people.
Manafort had been under house arrest since October when he was first hit with what became a series of criminal indictments related to his consulting work for pro-Russian politicians in Ukraine.
"I cannot turn a blind eye" to the ways Manafort has "abused the trust" of the court, Judge Amy Berman Jackson said as she yanked his bail and ordered him locked up pending his upcoming two federal criminal trials.
"This is not middle school. I can't take his cellphone," Jackson said as she rejected a suggestion by Manafort lawyer Richard Westling that she only modify his bail by barring him from contacting potential witnesses.
Jackson said that although there is "no evidence of even a threat of harm to any person" by Manafort, the harm from new charges "is harm to the administration of justice" and "to the integrity of the system."
The judge said her "extraordinarily difficult decision" was "not about politics," but instead about Manafort's conduct.
Prosecutors told Jackson during the hearing that Manafort and Kilimnik had made many attempts to contact potential witnesses during a five-week period earlier this year.
Mueller's team in an earlier court filing said Manafort's "obstructive" conduct, which included reaching out to the potential witnesses by using encrypted message apps, "instills little confidence that restrictions short of detention will assure Manafort's compliance with the court's orders and prevent him from committing further crimes."
Manafort was stone-faced as he left the courtroom headed to a jail cell, without having been handcuffed. He gave a quick wave in the direction of his defense team and his wife, Kathleen.
Jackson denied a request by Westling to delay jailing Manafort so that he could appeal her decision.
Kilimnik was not at the hearing. He is believed to be in Russia.
President Donald Trump called Manafort's jailing "very unfair" in a tweet almost two hours after he was ordered detained.
During the hearing, at which Manafort also pleaded not guilty to the witness tampering charges, Jackson pressed a prosecutor on whether Manafort currently represented a danger to the public.
The prosecutor said Manafort is a threat because of the likelihood that he will commit new crimes.
The prosecutor said Manafort, a day after being hit with a revised criminal indictment on Feb. 23, phoned a principal in a public relations firm who had worked on an effort to lobby for the nation of Ukraine. The effort involved a group of former European politicians known as the Hapsburg Group.
Manafort called the PR man, identified only as D1, while that man was a passenger in a car driven by his wife in Italy, the prosecutor said.
"This is Paul, Paul Manafort. I need to give you a heads up about the Hapsburg Group," Manafort said, according to the prosecutor.
D1 immediately hung up, the prosecutor said.
Mueller's team has said that two days later, Manafort sent D1 an encrypted message containing an article related to the Hapsburg Group, adding in the note: "We should talk. I have made it clear that they worked in Europe."
D1 has told Mueller's investigators that he believed Manafort was trying to get him to falsely state that the Hapsburg Group had limited its lobbying efforts to Europe. In fact, the group had also sought to influence opinion in the United States, without registering as required.
However, Westling scoffed at the idea that his client was trying to tamper with a witness.
Westling said the charge of witness tampering was unfair because Manafort had not been warned in advance by prosecutors that the people he was contacting were witnesses.
Manafort, a long-time Republican lobbyist and political consultant, was originally indicted last fall.
His first trial is scheduled to start in late July in U.S. District Court in Alexandria, Virginia. The second, in Washington, is scheduled for September.
Kilimnik, who is suspected of connections to Russian intelligence services, was a longtime employee of Manafort's political consulting groups and did work for him in Ukraine. He had not been charged before the indictment released June 8 accusing him and Manafort of witness tampering.
Before the hearing, while speaking to reporters outside the White House on Friday morning, Trump was asked about Manafort.
"Manafort has nothing to do with our campaign," Trump said. "I feel a little badly about it."
"You know, Paul Manafort worked for me for a very short period of time. He worked for Ronald Reagan. He worked for Bob Dole. He worked for many other he worked for me, what, 49 days or something. Very short period of time."
In fact, Manafort served 144 days as Trump's presidential campaign chairman. He was hired in late March 2016 and resigned five months later, on Aug. 19.
The charges that Manafort already was facing in Washington include conspiracy to defraud the United States, money laundering, acting as an unregistered agent of a foreign principal and making false statements.
The charges in Virginia include bank fraud, conspiracy and filing false tax returns.
Manafort's co-defendant and former business associate, Rick Gates, pleaded guilty in February to conspiracy against the United States and to making a false statement. Gates also had worked on Trump's election campaign.