Mike Waltz is to leave his current position as national security advisor to fill the American ambassadorship to the UN, per a Thursday post from President Donald Trump’s TRUTH social media account.

Secretary of State Marco Rubio will serve as interim national security advisor.

Waltz had been heavily criticized for his involvement in the Signalgate scandal, in which he included Jeffery Goldberg, the editor-in-chief of the Atlantic, in a groupchat where sensitive national security information was shared. Trump defended Waltz in the aftermath of the scandal, but reports indicate that the national security advisor lost the president’s confidence in the role.

Rep. Elise Stefanik (R-NY) had previously been the Trump nominee for UN ambassador, but her nomination was pulled as the White House sought to preserve thin GOP margins in the House of Representatives.

Editor’s note: This story has been updated with Trump’s statement about Waltz’s reassignment.