It's a major acknowledgment from the Mueller team that their investigation into Russian interference in the 2016 election is finding potential contact between at least one Trump campaign official and the Kremlin.
The peace plan refers to the conflict that erupted in Ukraine in 2014, after President Viktor Yanukovych fled the country amid mass protests.
The filing contains new details about his connection to Konstantin Kilimnik, a Russian-Ukrainian business associate who was indicted previous year on charges he tampered with potential witnesses. This includes his connection with former business partner Konstanin Kilimnik, a Ukrainian accused by prosecutors of having ties to Russian intelligence.
That's according to a court filing from defense lawyers Tuesday responding to allegations that Manafort has repeatedly lied to special counsel Robert Mueller's team of investigators.
U.S. District Judge Amy Berman Jackson gave Manafort's lawyers until Monday to respond to the allegation in writing and said prosecutors must provide their underlying evidence by January 14.
Trump has previously defended Manafort in comments to reporters, saying that his former campaign manager "has nothing to do with our campaign, but I will tell you I feel a little badly about it".
The inadvertent disclosures offered a rare glimpse into details that were meant to remain private while Manafort's lawyers and Mueller's office battle over whether Manafort has breached a plea agreement struck in September by lying.
The filing also showed that Mueller accused Manafort of discussing a "Ukraine peace plan" with Kilimnik and meeting with him in Madrid at some point during the 2016 campaign.
The lawyers further stated that Manafort's time in solitary confinement has negatively impacted his state of mind, and he was not able to prepare for his meetings with federal prosecutors. After being told that Mr. Kilimnik had traveled to Madrid on the same day that Mr. Manafort was in Madrid, Mr. Manafort "acknowledged" that he and Mr.Kilimnik met while they were both in Madrid.
U.S. District Judge Amy Berman Jackson demanded in a December 11 hearing that prosecutors provide more details to allow her to determine whether Manafortfailed to fully cooperate as required under his deal, and should face tougher sentencing.
Manafort's attorneys disputed the characterization Manafort authorized the unnamed person to communicate with Trump on his behalf, according to the redacted details of the filing, The Hill reported. The filing claims that the first alleged lie by Manafort was "related to a text message from a third-party asking permission to use Mr. Manafort's name as an introduction in the event the third-party met the President", which they argue "did not constitute outreach to the President".
Manafort, 69, has been in jail since June 15, when U.S. District Judge Amy Berman Jackson ordered him locked up after Mueller accused him and Kilimnik of witness tampering.
Prosecutors said Manafort also lied about the circumstances of a $125,000 wire transfer in 2017.
Manafort is scheduled to be sentenced on February 8 for his Virginia jury convictions for bank and tax fraud.
He later pleaded guilty in a separate case to two counts of conspiracy to avoid a second trial in Washington, D.C.
The ex-Trump aide had been hoping for leniency at his 5 March sentencing under the plea deal.