National security adviser H.R. McMaster is leaving the Trump administration.

He resigned after longstanding rumors of his ouster. John Bolton, a former US ambassador to the UN, is set to replace him.

McMaster's military bearing reportedly grated on Trump, who sometimes tuned McMaster out during briefings.



President Donald Trump's national security adviser, Army Lt. Gen. H.R. McMaster, is out. John Bolton, a former US ambassador to the UN, is set to replace him.

"I am thankful to President Donald J. Trump for the opportunity to serve him and our nation as national security advisor," McMaster said in a statement on Thursday.

"I am grateful for the friendship and support of the members of the National Security Council who worked together to provide the President with the best options to protect and advance our national interests."

McMaster's tenure was rocky and marked by disputes with his boss and other senior administration officials. Rumors bubbled up periodically that McMaster might be fired, but he had remained with the administration until now.

Trump had some conciliatory words for the three-star general on Thursday, saying "McMaster’s leadership of the National Security Council staff has helped my administration accomplish great things to bolster America’s national security."

Trump continued:

"He helped develop our America First National Security Strategy, revitalize our alliances in the Middle East, smash ISIS, bring North Korea to the table, and strengthen our nation’s prosperity. This work and those achievements will ensure that America builds on its economic and military advantages. I thank General McMaster and his family for their service and wish them the very best.”

People familiar with plans for an ouster said Trump was willing to take time with McMaster's departure to make sure he was not humiliated and to have a qualified successor in place, The Washington Post reported last week.

Bolton had been seen as a troubling pick for the National Security Council. He has been called a "dangerous man" by the former chief White House ethics lawyer Richard Painter.

"John Bolton was by far the most dangerous man we had in the entire eight years of the Bush Administration," Painter tweeted last Friday. "Hiring him as the president's top national security advisor is an invitation to war, perhaps nuclear war," he said.

Trump and Bolton had reportedly been discussing for weeks how to move him into McMaster's role, CNN White House correspondent Kaitlan Collins said on Thursday, citing a source familiar with the discussions. "Bolton promised Trump 'he wouldn't start any wars' if he selected him as the new national security adviser," Collins said.

Reports of rifts between McMaster and Trump had circulated for some time. McMaster's military bearing reportedly grated on Trump, who sometimes tuned McMaster out during briefings, Axios reported in July 2017.

McMaster is only the latest Trump administration official to make an exit. Earlier this month, Secretary of State Rex Tillerson learned of his termination from Trump's tweet announcing it. Before that, Gary Cohn, Trump's top economic adviser, quit over disagreements with trade policy.

"There will always be change," Trump previously told reporters. "And I think you want to see change. I want to also see different ideas."

McMaster was named national security adviser on February 20, 2017, taking over the post after the resignation of Michael Flynn.