National security advisor Mike Waltz is expected to step down on Thursday in the first shake-up among the president’s top advisors.,The development, reported first by CBS News, comes just over a month after Waltz faced a barrage of criticism for adding The Atlantic editor Jeffrey Goldberg to a groupchat on Signal in which cabinet officials discussed war plans for a strike in Yemen.

White House national security adviser Mike Waltz is leaving the administration just weeks after it was revealed he added a journalist to a Signal chat being used to discuss military plans, according to two people familiar with the matter Thursday.

Mike Waltz has been a dead man walking in the White House for the past month, and the outgoing national security adviser started to act like it, Trump administration sources tell