Rep. Elijah Cummings (D-MD), the chairman of the House Oversight Committee, revealed in a letter to White House counsel Thursday that Jared Kushner’s lawyer said in December that he “continues to use” WhatsApp to conduct official White House business.

Kushner’s lawyer Abbe Lowell also reportedly told Cummings that he wasn’t sure whether Kushner had ever used the messaging app to transmit classified information. The criticism of Kushner was part of a much longer letter rebuking counsel Pat Cipollone for the White House’s refusal to provide documents that the committee has requested. Cummings indicated that he could subpoena the documents if the White House does not cooperate.

Lowell disputed Cummings’ account of their December conversation: “I specifically said that ‘If there was a question about Jared’s use of WhatsApp, that is a question for White House counsel, not me,” he told Politico. Read more at Politico.