syria. mattis was originally supposed to stay on through february. then president trump announced the deputy defense secretary, patrick shanahan would be taking over as acting secretary on january 1. lucas tomlinson reporting live at the pentagon. lucas? >> trace, in his first meeting as acting defense secretary, patrick shanahan told senior leaders here to remember china, china, china. a sign that this new defense chief plans to ramp up focus on china. shanahan arrived at the pentagon bright and early at the pentagon's river entrance just before sunrise. >> priority number 1. >> at the white house a short time ago, president trump kept up his attacks on his former defense secretary jim mattis. the president says he fired mattis. >> what has he done for me? how has he done in afghanistan? not too good.