WASHINGTON (AP) — President Donald Trump on Wednesday named Robert O'Brien, his chief hostage negotiator and an established figure in Republican policy circles, as his new national security adviser.

O'Brien, the fourth person in two years to hold the job, becomes the administration's point person on national security amid rising tensions with Iran following the weekend attack on Saudi oil installations and fresh uncertainty in Afghanistan after the halt in peace talks with the Taliban.

The announcement of O'Brien's selection comes a week after Trump ousted John Bolton from the post, citing pol...