Posted on · O'Brien has been working in the State Department as the administration's hostage negotiator. He'll replace former Ambassador John Bolton, who parted company with Trump.
Posted on · Bolton takes the job as two major foreign policy challenges come to a head, in North Korea and Iran. He replaces H.R. McMaster, becoming the third man to hold the position under President Trump.
Posted on · According to inside accounts, the president and McMaster clashed when the top aide's cerebral briefings crashed into Trump's more freewheeling style