Senior members of the Trump administration’s National Security Council — including its top national security adviser, Michael Waltz — used Gmail to conduct government business, The Washington Post reported, citing documents and three unnamed government officials.

Waltz and at least one senior aide used the commercial email service to discuss sensitive government matters, The Washington Post reported.

U.S. National Security Advisor Mike Waltz received emails via his personal email account but has never used that account to send classified material, the White House said after The Washington Post reported Waltz and other National Security Council members used Gmail for government work.