Trump Names Robert O’Brien, Hostage Mediator, as National Security Adviser

LOS ANGELES — President Trump selected Robert C. O’Brien, the State Department’s chief hostage negotiator, to become his national security adviser on Wednesday, moving to reconstitute his foreign policy staff even as he faces rising tension with Iran.

Mr. Trump announced the selection on Twitter shortly after saying he would also “substantially increase Sanctions” on Iran following weekend attacks on oil facilities in Saudi Arabia that officials in Washington and the region have blamed on the Tehran government.

In choosing Mr. O’Brien to replace John R. Bolton, who left the White House last week, the president tapped a longtime lawyer who has impressed him with his work to extricate Americans detained by countries like North Korea and Turkey.

Mr. O’Brien, a founding partner of the law firm Larson O’Brien, will be Mr. Trump’s fourth national security adviser in three years, the most any president has had in a first term.

This is a developing story. Check back for updates.