Hostage negotiator Robert O'Brien is Trump's new US national security adviser
18 September 2019, 21:04 | Updated: 18 September 2019, 22:07
Donald Trump has named lead US hostage negotiator Robert O'Brien as his new national security adviser.
He is the fourth person in two years to hold the job and his appointment comes after John Bolton was forced out last week.
The US president confirmed the appointment on Twitter, writing that he had "worked long and hard with Robert. He will do a great job!"
Mr O'Brien starts the job at a time of heightened tensions with Iran after claims it was behind an attack on Saudi oil facilities.
There is also fresh uncertainty over Afghanistan after a halt in peace talks with the Taliban.
Robert O'Brien is a lawyer who co-founded his own firm in Los Angeles and has worked on cases of US hostages abroad.
In February he helped win the release of US engineer Danny Burch, who had been held hostage in Yemen for 18 months.
He also made headlines in July when he was sent to Sweden to oversee the assault trial of American rapper A$AP Rocky.
Mr O'Brien has long worked in foreign policy roles for the government.
He previously led a push for justice reform in Afghanistan during the Bush and Obama administrations.
From 2008 to 2011, he was a member of a government committee that advises on issues around the trafficking of antiquities and other cultural items.
In 2005, George W Bush nominated him to be representative to the UN General Assembly - where he worked with Mr Bolton.
He also was a foreign policy adviser on the presidential campaigns of Republicans Scott Walker, Mitt Romney and Texas senator Ted Cruz.
Before that, he was a legal officer for the UN Security Council commission that decided claims against Iraq from the Gulf War.
He was also a major in the US Army Reserve.
Mr O'Brien is a fierce critic of former president Barack Obama and is author of a collection of essays on US national security and foreign policy entitled While America Slept, slated as a "wake-up call to the American people".
His views on Iran are laid bare in the book, in which he writes: "The Islamic Republic of Iran is the largest state sponsor of terrorism in the world and is building an archipelago across the Middle East using proxies and Revolutionary Guard forces from Yemen to Syria to Lebanon."
His predecessor, Mr Bolton, was ousted over his approach to policy issues such as Iran and Afghanistan .
Mr Trump said he had told him "his services were no longer needed", but Mr Bolton insisted he had resigned.
H R McMaster and Michael Flynn previously held the national security job under Mr Trump.