The US Department of Treasury announced today (Dec. 19) that it is planning to lift sanctions imposed on three Russian companies controlled by a Russian oligarch who’s come up in the special counsel investigation into Russian meddling in the 2016 presidential election.

In a letter to Senate majority leader Mitch McConnell, the Treasury said it will end sanctions to En+Group, U Rusal, and EuroSibEnergy in 30 days.

The companies are controlled by Russian oligarch Oleg Deripaska, who has deep connections to Paul Manafort, Donald Trump’s former campaign chairman. Deripaska invested $18.9 million into a Ukrainian telecom venture ran by Manafort, but was never paid back. Special counsel Robert Mueller has reportedly investigated the links between the two men as part of his probe into Russia’s electoral interference.

Deripaska, who is close to Vladimir Putin, was “accused of threatening the lives of business rivals, illegally wiretapping a government official, and taking part in extortion and racketeering” when the Treasury hit him with sanctions in April.

At the time, the Treasury also imposed sanctions on the three companies as a way to hit Deripaska. But the agency said Wednesday that it will no longer sanction them, because they have agreed to distance themselves from the oligarch. “These companies have committed to significantly diminish Deripaska’s ownership and sever his control,” Treasury secretary Steven Mnuchin said in a statement. They will suffer ”severe consequences” should they not comply, he added.

The Treasury said it will remove sanctions from any venture in which Deripaska has less than 50% ownership, though the oligarch will still be subject to them personally.