1. Rex Tillerson apparently learned of his dismissal by being shown President Trump’s tweet naming Mike Pompeo, the C.I.A. director, as secretary of state.

Mr. Pompeo opposes the Iran nuclear deal and doubts that talks will persuade North Korea to give up its nukes.

The Senate must confirm his appointment, as well as that of his replacement. Gina Haspel, his current deputy, would be the first woman to head the C.I.A. She has had a leading role in the torture of detainees.