Mattis met with Trump in the White House to make his case — and after he quit, the former general sent Trump a scathing resignation letter that focused on his belief in strong relationships with US allies.
“One core belief I have always held is that our strength as a nation is inextricably linked to the strength of our unique and comprehensive system of alliances and partnerships,” wrote Mattis.
Trump announced on Wednesday that US troops would completely pull out of Syria and declared that the US had “defeated ISIS” in the country.
Aside from Syria, Mattis and Trump have reportedly clashed over a host of foreign policy issues, including the US-NATO relationship, military exercises in South Korea and Trump’s decision to pull out of the Iran-nuclear deal.