“Over the last several months, we have worked cooperatively with each of the committees and have voluntarily turned over thousands of documents in response to their requests,” said Alan Futerfas, an attorney for Donald Trump Jr. “Putting aside the question as to why or by whom such documents, provided to Congress under promises of confidentiality, have been selectively leaked, we can say with confidence that we have no concerns about these documents and any questions raised about them have been easily answered in the appropriate forum.” WikiLeaks did not respond to requests for comment.

The messages were turned over to Congress as part of that body’s various ongoing investigations into Russian meddling in the 2016 presidential campaign. American intelligence services have accused the Kremlin of engaging in a deliberate effort to boost President Donald Trump’s chances while bringing down his Democratic rival, Hillary Clinton. That effort—and the president’s response to it—has spawned multiple congressional investigations, and a special counsel inquiry that has led to the indictment of Trump’s former campaign chair, Paul Manafort, for financial crimes.

It’s not clear what investigators will make of the correspondence, which represents a small portion of the thousands of documents Donald Trump Jr.’s lawyer says he turned over to them. The stakes for the Trump family, however, are high. Trump Jr.’s June 2016 meeting with Natalia Veselnitskaya, a Russian lawyer with connections to Russia’s powerful prosecutor general, is already reportedly a subject of interest in Special Counsel Robert Mueller’s investigation, as is the White House statement defending him. (Trump Jr. was emailed an offer of “information that would incriminate Hillary,” and responded in part, “If it’s what you say I love it.”) The messages exchanged with WikiLeaks add a second instance in which Trump Jr. appears eager to obtain damaging information about Hillary Clinton, despite its provenance.

Though Trump Jr. mostly ignored the frequent messages from WikiLeaks, he at times appears to have acted on its requests. When WikiLeaks first reached out to Trump Jr. about putintrump.org, for instance, Trump Jr. followed up on his promise to “ask around.” According to a source familiar with the congressional investigations into Russian interference with the 2016 campaign, who requested anonymity because the investigation is ongoing, on the same day that Trump Jr. received the first message from WikiLeaks, he emailed other senior officials with the Trump campaign, including Steve Bannon, Kellyanne Conway, Brad Parscale, and Trump son-in-law Jared Kushner, telling them WikiLeaks had made contact. Kushner then forwarded the email to campaign communications staffer Hope Hicks. At no point during the 10-month correspondence does Trump Jr. rebuff WikiLeaks, which had published stolen documents and was already observed to be releasing information that benefited Russian interests.