Defense Secretary James "Mad Dog" Mattis resigned from his position effective February 28. He disagreed with the president's decision. It was the second time in five years that an elected commander in chief had a serious conflict with Mattis' hawkishness. President Obama fired him as Central Command chief for urging a more aggressive Iran policy. Mattis is also extremely hawkish towards Russia and China.

President Trump campaigned on lessening U.S. involvement in wars abroad. He wants to get reelected. He does not need a Secretary of Defense that involves him in more wars that have little to none defined purpose.

Mattis is an ingrained imperialist. He always asked for more money for the military and for more meddling abroad.