A consulting firm led by Paul Manafort, who chaired Donald Trump’s presidential campaign for several months last year, retroactively filed forms Tuesday showing that his firm received $17.1 million over two years from a political party that dominated Ukraine before its leader fled to Russia in 2014.

Manafort disclosed the total payments his firm received between 2012 and 2014 in a Foreign Agents Registration Act filing late Tuesday that was submitted to the U.S. Justice Department. The report makes Manafort the second former senior Trump adviser to acknowledge the need to disclose work for foreign interests.

Manafort is one of a number of Trump associates whose campaign activities are being scrutinized by Special Counsel Robert Mueller as part of a probe of Russian interference in the 2016 presidential election. Mueller’s team has been consolidating inquiries into matters unrelated to the election.

Manafort and a former associate in his consulting business, Richard Gates, who also worked for the Trump campaign, disclosed their lobbying campaign on behalf of Ukraine’s Party of Regions in an 87-page document which described the gross receipts the firm received and some details of efforts undertaken to influence U.S. policy toward Ukraine. The filing shows the firm spent nearly $4 million to advance the party’s interests through polling and local salaries in Ukraine, activity that does not ordinarily require U.S. disclosure.