President Trump announced today that he would remove his national security adviser, Michael Waltz, from his White House role and nominate him as ambassador to the United Nations. Trump tapped Secretary of State Marco Rubio as Waltz’s interim replacement; he will remain as the nation’s top diplomat.

It was the first significant overhaul of Trump’s West Wing staff since he returned to office — the kind of change he had sought to avoid in an effort to minimize the headlines about chaos that engulfed his first term. Rubio will now be the first person since Henry Kissinger to lead both the State Department and the National Security Council.

My colleagues Maggie Haberman, David Sanger and Jonathan Swan explained what led to Waltz’s ouster. His position had become especially precarious after it became public that he organized a Signal group chat to discuss a sensitive military operation.

But before that, he had been on thin ice for months. Most of Trump’s advisers viewed Waltz as too hawkish to work for the president, who campaigned as a skeptic of American intervention and as eager to reach a nuclear deal with Iran and normalize relations with Russia. Waltz’s deputy, Alex Wong, who is considered a more moderate Republican and who has substantial national security experience, is also expected to be removed.