WASHINGTON (AP) — President Donald Trump says Defense Secretary Jim Mattis will leave his post on Jan. 1.

Trump announced Mattis’ new departure date in a tweet and said he’s naming deputy defense chief Patrick Shanahan as acting secretary.

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The move comes just three days after Mattis resigned in protest over Trump’s decision to pull all U.S. troops out of Syria. Mattis originally said he would stay through February to ensure an orderly transition.

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