mattis resigned in response to trump's abrupt troop withdrawal announcement issuing a clear rebuke of the president those same allies have been left stunned on a visit to chad french president a man who in my column was pretty clear about what he thought. before him all of this i do play regret the decision taken on syria and i would like to pay tribute here to general mattis and to the words that accompanied his decision. so this is you don't go in there you and i lie should be reliable and coordinate with other allies general mattis understood this perfectly. mattis will be replaced by his deputy patrick shanahan as acting defense secretary on january the first trump only brought shanahan into the defense department last year he's an engineer who spent most of his career at boeing a major supplier to u.s. forces he has no background in politics diplomacy or military affairs.