WASHINGTON, Sept 18 — US President Donald Trump today named US hostage negotiator Robert O’Brien as his choice to replace John Bolton as his national security adviser, making him the fourth person to hold the post in the Trump administration.

O’Brien, who has served as Trump’s special envoy for hostage affairs at the US Department of State since May 2018, has a long history in Republican foreign policy circles.

"I have worked long & hard with Robert. He will do a great job!” Trump wrote on Twitter.

O’Brien is an attorney from Los Angeles who has served as a foreign policy adviser to several Republican presidential campaigns, handled a number of high profile legal cases and previously served in several State Department positions, including as an alternative representative to the UN General Assembly in 2005.

Trump had been weighing a number of potential replacements after Bolton left the post last week following disagreements with the president over his handling of North Korea and Venezuela.

His previous national security advisers were H.R. McMaster, who was replaced by Bolton in March 2018, and Michael Flynn, who was fired shortly after taking the role and later pleaded guilty to lying to the FBI. — Reuters