U.S. Secretary of Defense Jim Mattis arrives for a closed intelligence briefing at the U.S. Capitol with members of the House of Representatives December 13, 2018 in Washington, DC.

In resignation letter to Trump, Mattis warns against getting too close to 'authoritarian' countries "During Jim’s tenure, tremendous progress has been made," Trump said.

President Donald Trump pauses while speaking as James Mattis, Secretary of Defense, listens during a Cabinet meeting at the White House in Washington, June 21, 2018.

General Jim Mattis, former U.S. Secretary of Defense under President Donald Trump, spoke about the need to preserve American moral ideals in a time of uncertainty and shifting values.

Late-night hosts Seth Meyers, Stephen Colbert, Jimmy Kimmel, and Jimmy Fallon addressed Former U.S. Secretary of Defense Jim Mattis' criticism of the president, Donald Trump's reaction, and the ...

Did Jim Mattis condemn Trump over LA protests? Learn how a 2020 statement by the retired general from Richland, WA, has been misrepresented online.

During a conversation with CNN's Don Lemon on Wednesday, General James "Spider" Marks and General Mark Hertling––both CNN military analysts––reacted to President Donald Trump trashing now ...