The Washington Post tells about its sources.
Members of the US National Security Council have used their personal Google Gmail email accounts in official administrative matters. Telling Washington Post based on their sources.
Gmail account has been used by, among other things, US National Security Adviser Mike Waltz. In addition, the magazine reports that one of Waltz’s assistants has sent emails from his account to process sensitive information about military destinations and weapon systems.
Unprotected email services are not considered secure in transmitting sensitive or encrypted information.