Trump pushes out James Mattis sooner than expected

Deputy Secretary of Defense Patrick Shanahan will become the acting secretary on January 1, President Trump tweeted on Sunday.

Why it matters: This is two months earlier than Secretary James Mattis announced last week, a delay meant to ensure a smooth transition. While Trump initially praised Mattis after announcing his exit, the secretary's stark letter seems to have turned Trump, who has since publicly criticized Mattis.