U.S. Commerce Secretary Wilbur Ross shares business interests with Russian President Vladimir Putin’s son-in-law, a connection that he failed to disclose earlier this year during his confirmation hearing for his Cabinet post, NBC News reports.

Ross’ link to Putin appears in the Paradise Papers, a leaked trove of millions of financial documents made public on Sunday by a partnership of media organizations and the International Consortium of Investigative Journalists.

Ross, a billionaire industrialist and a close friend of President Donald Trump, continues to hold a stake in a Russian shipping firm controlled by a Russian oligarch, Putin’s son-in-law, and other members of Putin’s inner circle, according to the documents.

Daniel Fried, an assistant secretary of state for European and Eurasian affairs under President George W. Bush, told The Guardian that Ross’ ties to Putin’s “cronies” could undermine U.S. sanctions on Russia.

In January, ahead of his confirmation, Ross agreed to sell some but not all of his global assets that posed a conflict of interest to his future position. He also agreed, as required by law, to recuse himself from matters in which he would have a direct financial interest.

Ross’ spokesman told The Guardian that his stake in the Russian firm would not conflict with his duties as commerce secretary and that Ross “recuses himself from any matters focused on transoceanic shipping vessels.”

Sen. Richard Blumenthal (D-Conn.), who sits on the Senate Commerce Committee, said Ross “misled” him and the committee by failing to disclose links to Russian interests.

“With Wilbur Ross revelations, question must be asked - whose interests come first in this Administration?” Blumenthal asked Sunday on Twitter.

Ross is only the latest high-ranking member of the Trump administration who failed to disclose ties to Russia or Russian officials.

Attorney General Jeff Sessions is being called by Democrats to testify again before the Senate Judiciary Committee to clarify past claims that he was unaware of any communication between members of Trump’s presidential campaign and Russian officials. According to recently unsealed court documents, former Trump campaign foreign policy adviser George Papadopoulos spoke multiple times with Russians about setting up a meeting between Putin and then-presidential candidate Trump, and that Sessions was at the gatherings where Papadopoulos discussed the topic.

Papadopoulos has pleaded guilty to lying to the FBI about his conversations with Russian officials during the presidential campaign. The plea came as part of Special Counsel Robert Mueller’s investigation into Russian meddling in the 2016 election.

This post was updated with reaction from Sen. Blumenthal.