US President Donald Trump says he's naming hostage negotiator Robert O'Brien as his new national security adviser.
O'Brien monitored the recent criminal case in Sweden against American rapper A$AP Rocky.
Trump tweeted the announcement from California, where he was opening the third and final day of a West Coast fundraising swing.
"I am pleased to announce that I will name Robert C. O'Brien, currently serving as the very successful Special Presidential Envoy for Hostage Affairs at the State Department, as our new National Security Advisor," Trump said on Wednesday.
"I have worked long & hard with Robert. He will do a great job!"
Trump announced that O'Brien will become his fourth national security adviser a week after he ousted John Bolton , citing policy disagreements.
O'Brien was among five candidates the Republican president had said on Tuesday were being considered for the post, which does not require Senate confirmation.
As the special presidential envoy for hostage affairs at the State Department, O'Brien worked closely with the families of American hostages and advised administration officials on hostage issues.
A former major in the US Army Reserve, he also previously helped lead the department's public-private partnership for justice reform in Afghanistan during the Bush and Obama administrations.
Earlier this year, Trump dispatched O'Brien to Sweden to keep tabs on the criminal case there against A$AP Rocky.
A judge and jury ultimately found the rapper guilty of assault in August, several weeks after a street brawl in Stockholm that attracted Trump's attention.
O'Brien 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.