President Donald Trump announced Wednesday that he's chosen Robert C. O'Brien to succeed John Bolton as his next national security adviser.

>> Read more trending news

The president announced his choice, which does not require confirmation from the U.S. Senate, in a tweet.

"I have worked long & hard with Robert," he wrote. "He will do a great job!"

Since May 2018, O'Brien has served as an ambassador with the U.S. Special Presidential Envoy for Hostage Affairs at the State Department. He is a co-founding partner at the Los Angeles-based Larson O'Brien LLP law firm, where he's focused on international arbitration.

O'Brien will become Trump's fourth national security adviser, replacing Bolton, who was ousted last week over disagreements with the president over how to deal with Iran, Afghanistan and a host of global challenges.

Bolton had been skeptical about the president's whirlwind rapprochement with North Korea since he joined the administration last year and recently became a vocal critic of potential talks between Trump, leaders of the Afghan Taliban and Iran.

Trump said he had "disagreed strongly" with many of Bolton's suggestions as national security adviser, "as did others in the administration."

The Associated Press contributed to this report.