US President Mike Pence's national security adviser added The Atlantic editor-in-chief Jeffrey Goldberg to his Signal chat instead of National Security Council spokesman Brian Hughes because his number was incorrectly recorded, CBS reported, citing its sources.
Goldberg sent a letter to US President Donald Trump's campaign in October last year.
Hughes forwarded the message to Walz, who saved Goldberg's number as Hughes' new number.
An internal investigation showed that no White House staff had previously contacted the editor-in-chief of The Atlantic.
It is noted that Walz called and texted Hughes' real number many times.
According to CBS, the mix-up occurred during the US national security adviser's trip to Saudi Arabia for talks with the Ukrainian delegation in early March.
When he created the chat, he used the wrong number for Hughes.
Goldberg published an article on March 24 in which he said that on March 11 he received an invitation to connect with the Signal messenger by a user with the pseudonym Mike Walz.
Two days later, the journalist received a notification that he had been included in a group chat in which members of the US administration were discussing strikes on Yemen.
According to the journalist, on March 15, a user under the pseudonym Pete Hegseth published a message with details of the upcoming strikes against the Houthis and the expected time of the operation, which, according to Goldberg, coincided with the publication of the first reports of the strikes.
On March 15, the United States, on the orders of Trump, began carrying out massive strikes on Houthi targets, who control about a third of the territory of Yemen.
The US Democratic Party considers the data leak via Signal a major failure of the Republican Trump administration.
There are calls in the US Congress and the American expert community for the dismissal of Walz and other representatives of the presidential team.