Trump names new national security adviser

United States president, Donald Trump, on Wednesday appointed Robert O’Brien as his new national security adviser.

Mr O’Brien, a lawyer who has worked at the U.S. State Department as chief hostage negotiator, was appointed a week after John Bolton left as the NSA.

Mr. O’Brien will be Mr. Trump’s fourth national security adviser in three years of his administration, marking the most any American president has had in a first term.

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Mr Trump made the announcement on Twitter Wednesday morning, as he moved to reconstitute his foreign policy team amidst growing tension with Iran.

Mr Trump said he would ramp up sanctions on Iran, a country he has regularly maligned as dangerous and unstable.