President Trump has named his pick to succeed John Bolton as the next National Security Advisor amid burgeoning tensions with Iran over a weekend attack in Saudi Arabia.

In a Wednesday morning tweet, Trump said he planned to nominate Robert C. O'Brien, who currently serves as the special presidential envoy for hostage affairs at the State Department, the administration's top hostage negotiator, to become the next NSA.

According to the State Department's website, O'Brien has served in multiple administrations, and even once worked closely with John Bolton after being named the US representative to the 60th session of the UN General Assembly by George W Bush.