The new indictment charges Manafort and Kilimnik with obstruction of justice and conspiracy to obstruct justice related to contacts they had with two witnesses earlier this year.
The alleged coverup stems from work Manafort, Kilimnik and others did with former European politicians, referred to informally as the "Hapsburg group", to advocate on Ukraine's behalf to US and European officials.
Trump has recently tried to distance himself from Manafort, tweeting last week that the longtime Republican consultant joined his campaign at a "very late" stage and "was with us for a short period of time".
It was the third time Mueller had added to charges against Manafort. Manafort's lawyers would find the hard work of trial preparation even more challenging with their client in jail, Zeidenberg said.
In previous court filings Mueller's team has referred to Kilimnik as "Person A", someone "who is now based in Russia and assessed to have ties to a Russian intelligence service".
Kilimnik is believed to be in Moscow and therefore likely safe from arrest, because Russian Federation does not extradite its citizens.
The charges, placed by special counsel Robert Mueller, who is investigating possible collusion between Donald Trump and Russian Federation in the run-up to the 2016 election, increase Manafort's legal jeopardy if he continues an aggressive battle with prosecutors.
Manafort relied heavily on Kilimnik throughout his decade-long work in Ukraine. The country was ousted from the leading group of industrialised nations in 2014 as punishment for President Vladimir Putin's annexation of Crimea and its support for pro-Russian separatists in Ukraine.
Manafort has acknowledged staying in frequent contact with Kilimnik during the time he worked for Trump's campaign.
"You don't really care about Mr. Manafort", U.S. District Judge T.S. Ellis III told Mueller's team. A hearing is set for next week. Manafort was accused of violating the gag order by co-ghostwriting an op-ed meant to make him look good in the media. Kilimnik was also involved in that episode.
Manafort and Kilimnik's allegedly criminal contact with the two witnesses who once worked with them doing public relations began on a day, February 23, when Manafort's case became far tougher to overcome. Among other things, they also affect the business partner Manafort of Ukraine Konstantin Kilimnik. He has been charged with money laundering, tax and bank fraud, and conspiracy in two federal cases as part of Mueller's ongoing probe.
Mueller has accused Manafort of attempting to call, text and send encrypted messages in February to two people from "The Hapsburg Group", a political discussion group he allegedly worked with to promote the interests of Ukraine, in an effort to influence their testimony or hide evidence in the case. "Manafort done it without registration or providing notification, as required by law", - stated in the text. "Closer scrutiny of this "evidence" reveals that the Special Counsel's allegations are without merit because Mr. Manafort's limited communications can not be fairly read, either factually or legally, to reflect an intent to corruptly influence a trial witness".
Prosecutors said the two didn't respond to the communications from Manafort and the associate, with one of them telling prosecutors he believed they were trying to induce him to commit perjury.
Kilimnik wasn't identified by name in the March filing but Bloomberg has confirmed it referred to him. He also has denied being connected to Russian intelligence agencies.
Asked on Friday if he would pardon Manafort, Trump refused to answer.