U.S. President Donald Trump clipped the wings of perhaps the most hawkish member of his inner circle on Tuesday, firing national security adviser John Bolton in a move expected to have repercussions for Japan and American foreign policy in Asia.

Trump, who said he had disagreed "strongly" with Bolton on policy, announced via Twitter: "I asked John for his resignation, which was given to me this morning."

A replacement — the White House's fourth national security chief in less than three years — will be named next week, Trump said.