President Donald Trump says he fired Jim Mattis as defense secretary. But the retired Marine general actually resigned in protest over Trump's decision to pull U.S. troops from Syria.

  

Mattis announced on Dec. 20 that he was stepping down, but would stay on the job until the end of February. Three days later, Trump said he was replacing Mattis with the second-ranking defense official, Pat Shanahan, on New Year's Day.

  

At a Cabinet meeting Wednesday, Trump said Mattis "couldn't believe" how much federal money Trump had helped secure for the military.

  

Trump then asked rhetorically "What's he done for me?"

  

Trump also said he wasn't happy with Mattis' work in Afghanistan. Trump says the U.S. should let the Taliban and Islamic State militants fight each other there.