US President Donald Trump, right, and his White House national security adviser, Mike Waltz. Photo: REUTERS/Kevin Lamarque

US President Donald Trump ousted his national security adviser Mike Waltz on Thursday and named Secretary of State Marco Rubio as his interim replacement in the first major shakeup of Trump’s inner circle since he took office in January.

Trump, in a social media post, said he would be nominating Waltz to be the next US ambassador to the United Nations, adding that “he has worked hard to put our nation’s interests first.”

Earlier in the day, sources said Trump had decided to force Waltz out of his White House position.

Trump’s selection of Rubio to replace Waltz temporarily will be the first time since Henry Kissinger in the 1970s that one person held both the positions of secretary of state and national security adviser.

Waltz‘s deputy, Alex Wong, an Asia expert who was a State Department official focused on North Korea during Trump’s first term, is also leaving his post, two people familiar with the matter told Reuters.

Waltz, a 51-year-old former Republican lawmaker from Florida, faced criticism inside the White House when he was caught up in a March scandal involving a Signal chat among top Trump national security aides.

The national security adviser is a powerful role that does not require Senate confirmation.