• President Donald Trump plans to nominate his national security advisor Mike Waltz to be the U.S. ambassador to the United Nations.
• Trump's announcement came hours after multiple news reports that Walz would leave his post as national security advisor amid continued controversy over his creation of a Signal messaging app chat thread that was used by Defense Secretary Pete Hegseth to reveal U.S. military plans.
• The president had previously nominated Rep. Elise Stefanik, R-N.Y., for the U.N. ambassador slot.
• Trump withdrew Stefanik's nomination in late March, citing the very slim majority that Republicans hold in the House of Representatives.

President Donald Trump said Thursday that he will nominate to be the U.S. ambassador to the United Nations, confirming earlier reports that Waltz was being ousted as national security advisor.

Trump said that Secretary of State Marco Rubio would serve as interim national security advisor until that post is filled.

The announcement came hours after multiple news reports that Walz would leave that role amid continued controversy over his creation of a messaging app chat thread that was used by to reveal U.S. military plans to other Trump administration officials.

The editor of The Atlantic magazine had been inadvertently added to the chat thread by Waltz.

The president had previously nominated , R-N.Y., for the U.N. ambassador slot.

But Trump withdrew Stefanik's nomination in late March, citing the very slim majority that Republicans hold in the House of Representatives.

"I am pleased to announce that I will be nominating Mike Waltz to be the next United States Ambassador to the United Nations," Trump wrote in a Truth Social post on Thursday.

"From his time in uniform on the battlefield, in Congress and, as my National Security Advisor, Mike Waltz has worked hard to put our Nation's Interests first. I know he will do the same in his new role," Trump wrote.

"In the interim, Secretary of State Marco Rubio will serve as National Security Advisor, while continuing his strong leadership at the State Department. Together, we will continue to fight tirelessly to Make America, and the World, SAFE AGAIN. Thank you for your attention to this matter!"

Waltz, in a tweet replying to Trump's post, wrote, "I'm deeply honored to continue my service to President Trump and our great nation."

Waltz, 51, previously served in the House, representing a Florida district. Earlier, he served in the U.S. Army as a Special Forces officer.

State Department Spokeswoman Tammy Bruce was asked at a briefing Thursday how long Rubio would stay in the interim role as national security advisor.

'It is clear that I just heard this from you," Bruce told the reporter who asked that question.

In February, Trump appointed Rubio as acting administrator of the U.S. Agency for International Development.

Rubio is also the acting archivist of the United States.

Henry Kissinger, who served as President Richard Nixon's national security advisor, retained that position after Nixon appointed him secretary of state in 1973.

Kissinger retained both jobs under Nixon's successor, President Gerald Ford, until Ford installed Brent Scowcroft as national security advisor in November 1975.