Donald Trump says he plans to name hostage negotiator Robert O'Brien as his new national security adviser.
The US president tweeted that he has "worked long & hard" with O'Brien and that "he will do a great job!"
His announcement comes a week after he ousted John Bolton from the national security adviser's post, citing policy disagreements.
Mr Bolton was Trump's third national security adviser.
His replacement Mr O'Brien was among five candidates Mr Trump said were under consideration.
As the special presidential envoy for hostage affairs at the State Department, Mr O'Brien worked closely with the families of American hostages.
He also advised administration officials on hostage issues.
He helped lead the department's public-private partnership for justice reform in Afghanistan during the Bush and Obama administrations.
From 2008 to 2011, Mr O'Brien was a presidentially appointed member of a government committee that advises on issues related to the trafficking of antiquities and other cultural items.
In 2005, President George W Bush nominated him to be US representative to the UN General Assembly, where he worked with Mr Bolton. Mr O'Brien was confirmed by the Senate.
He also was an adviser on the Republican presidential campaigns of former Wisconsin governor Scott Walker, ex-Massachusetts governor Mitt Romney and Texas senator Ted Cruz.
Earlier in his career, Mr O'Brien was a senior legal officer for the UN Security Council commission that decided claims against Iraq that arose from the Gulf War. He was a major in the US Army Reserve.
He has a law degree from the University of California-Berkeley and co-founded a law firm in Los Angeles focused on litigation and international arbitration issues.
Additional reporting by agencies.
