JUST IN: "Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position," Sec. Mattis says in resignation letter to Pres. Trump. https://t.co/nuTUUJQ45P pic.twitter.com/FMGBbPhVJW
— ABC News (@ABC) December 20, 2018