WikiLeaks made contact with Trump Jr. in late September 2016 and continued communicating with him through the first half of this year, he said. One source told ABC News the conversations were heavy in one direction, with WikiLeaks sending many messages to Trump and Trump responding on a limited basis, often ignoring them.
On Monday night, after initial reports of his communications with WikiLeaks surfaced, Trump tweeted what he said were screenshots of the exchanges with WikiLeaks over Twitter's direct message system.
Sources confirmed for ABC News that Trump has turned over his correspondence with WikiLeaks to congressional investigators — on the House Intelligence and Senate Intelligence and Judiciary committees — as part of the Russia investigations on Capitol Hill and to special counsel Robert Mueller's team.
Alan Futerfas, Trump's lawyer, said in a statement to ABC News that his client has cooperated with the various congressional investigations.
"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," Futerfas wrote. "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."
"We just see this web of connections becoming more and more extensive," Schiff said.
Vice President Mike Pence's office said he was not aware of Trump Jr.'s communications with WikiLeaks. In October 2016, Pence forcefully denied any coordination between WikiLeaks and the Trump campaign.
"The vice president was never aware of anyone associated with the campaign being in contact with WikiLeaks. He first learned of this news from a published report earlier tonight," Pence's press secretary Alyssa Farah said in a statement.
WikiLeaks founder Julian Assange tweeted that he couldn't confirm the communications with Trump.