WASHINGTON (AP) -- The sooner-than-expected departure of Defense Secretary Jim Mattis now shifts the focus to President Donald Trump's appointment of an acting Pentagon chief and plans for a permanent replacement.
It also signals an acrimonious end to a tense relationship between Trump and Mattis that had eroded in recent months. A fracture developed last week over Trump's decision to withdraw U.S. troops from Syria and worsened after Mattis' public disagreement with Trump, aired in Mattis' resignation letter.
Deputy Defense Secretary Patrick Shanahan will take over as acting secretary on Jan. 1, Trump announced in a tweet Sunday.
Mattis, a retired Marine Corps general, had been expected to retain his position as Pentagon chief through February. But that changed suddenly on Sunday when Trump tweeted that Mattis was out, and Shanahan in.