"Therefore, the Office of Special Counsel is no longer bound by its obligations under the plea agreement, including its promise to support a reduction of the offense level in the calculation of the U.S. Sentencing Guidelines for acceptance of responsibility," Jackson wrote in an order released on Wednesday evening.
Manafort is currently in jail, awaiting sentencing.
Specifically, the judge found that Manafort 'made multiple false statements' about 'his interactions and communications' with his associate Konstantin Kilimnik, a Russian political operative who had worked with Manafort on behalf of pro-Russian officials in Ukraine.
U.S. officials have long believed that Kilimnik has ties to Russian intelligence.
In heavily redacted documents submitted to the court in December, the Special Counsel's office alleged that Manafort had not told the truth repeatedly about his interactions with Kilimnik.
A separate filing by Manafort's lawyers - which included botched redactions - revealed that one question was whether Manafort had given campaign polling data about the Presidential election to Kilimnik during the campaign.
Judge Jackson ruled against the Special Counsel in two of five areas where Manafort's testimony was questioned, including one where she said that Manafort had not lied intentionally about "Kilimnik's role in the obstruction of justice conspiracy."
At this point, Manafort is scheduled for sentencing on March 13; but it's not clear if that will change in the wake of these findings by the judge.