Another White House departure.
H. R. McMaster, the emabattled US national security adviser, is being replaced by John R. Bolton, a hard-line former United States ambassador to the United Nations.
The move's expected to inject a hawkish foreign policy voice into Preident Trump's administration ahead of key decisions on Iran and North Korea.
Trump, who often clashed with McMaster, tweeted Thursday that McMaster has done "an outstanding job & will always remain my friend.''
He said Bolton will take over April 9th.
McMaster issued a statement expressing his thanks to President Trump.
CBS News political analyst Leonard Steinhorn says the president is surrounding himself with yes-men.
The news followed word that John Dowd, US Preident Trump's lead lawyer in the Russia investigation, resigned.