President Donald Trump, left, and H.R. McMaster, national security advisor, walk toward Marine One on the South Lawn of the White House in Washington, D.C., June 16, 2017.

John Bolton, a noted foreign policy hawk, will replace H.R. McMaster as President Donald Trump's national security advisor, the latest move in an ongoing shakeup of the president's top advisors.

In a tweet Thursday, Trump said Bolton, a former U.S. ambassador to the U.N., will take over the post on April 9. McMaster, an Army lieutenant general, "has done an outstanding job & will always remain my friend," the president wrote.

Trump tweet: I am pleased to announce that, effective 4/9/18, @AmbJohnBolton will be my new National Security Advisor. I am very thankful for the service of General H.R. McMaster who has done an outstanding job & will always remain my friend. There will be an official contact handover on 4/9.

In Bolton, who served as U.N. ambassador for parts of 2005 and 2006, Trump will get an advisor whom experts consider more in favor of military intervention around the globe than McMaster is. For instance, in February, he made the legal case in The Wall Street Journal for a pre-emptive strike on North Korea. In 2015 he wrote an op-ed for The New York Times titled "To Stop Iran's Bomb, Bomb Iran."

In a separate statement, McMaster said he is requesting retirement from the Army this summer, after which he will "leave public service." As recently as last week, the White House denied a string of reports saying McMaster could soon leave.

McMaster's exit is just the latest departure of a top Trump administration official announced in the last two weeks. Larry Kudlow recently replaced Gary Cohn as director of the National Economic Council, while Mike Pompeo is set to replace Rex Tillerson as secretary of State, pending Senate confirmation.