The new information comes from The Washington Post, which has seen documents that allegedly show this.
Waltz should not have sent sensitive material via his private Gmail account, but according to the newspaper, "potentially exploitable" documents, including schedules.
At least one high-ranking employee of Waltz has, however, used private email for sensitive military material about, among other things, weapon systems.
No evidence
A spokesperson for the National Security Council, Brian Hughes, tells The Washington Post that he has not seen any evidence that Waltz has used his private email as described by the newspaper.
Waltz did not and could not send classified information via an open account, he says.
The information comes after a week where Waltz was already in trouble for causing serious security breaches.
The new revelation is also close to the same security breaches as when former Secretary of State Hillary Clinton was exposed in 2015, and which not least Donald Trump was strongly – and loudly – critical of.
Last week, it was revealed that Waltz invited an American journalist to a group chat in the encrypted messaging service Signal, where ministers and top officials discussed military attacks on Yemen.
Trump in meeting about Waltz
Later in the week, it was reported that mobile numbers, email addresses, and in some cases passwords of ministers and high-ranking Trump officials – including Waltz – could be found among hacked data dumped online.
The President has publicly backed Waltz, but last Wednesday, he discussed the adviser's future with, among others, Vice President JD Vance and Chief of Staff Susie Wiles.
According to a source to The Washington Post, Waltz only got to keep his job because Trump did not want to give "liberal media a scalp".
