U.S. Defense Secretary Mark Esper was fired in a tweet on Monday, as President Donald Trump went after a top aide he blamed for not supporting him sufficiently.

Trump said he¡¯s naming Christopher Miller, the director of the National Counterterrorism Center, as acting Pentagon chief.

Esper¡¯s relationship with Trump soured after the defense secretary resisted Trump¡¯s inclination to use active-duty forces to quell protests in U.S. cities earlier this year.