Donald Trump has ousted HR McMaster as his national security adviser and will appoint hardliner John Bolton in his place, it emerged on Thursday.
The US president announced the news in a tweet, with the change set to take place on April 9.
The move comes despite repeated rebuttals from the White House over whether Mr McMaster would be removed from office.
It also continues a tumultuous period that has seen a string of major staff departures from the White House and the cabinet.
Mr McMaster, who had never met Mr Trump before being interviewed for the role, clashed with the president over the Iran nuclear deal and Afghanistan policy.
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