National Security Adviser Gen. H.R. McMaster out; former U.S. ambassador John Bolton in

National Security Adviser Gen. H.R. McMaster is resigning from the Trump administration and will be replaced by former U.S. ambassador John Bolton, according to a tweet Thursday afternoon from President Donald Trump.

>> Read more trending newsWho is H.R. McMaster, Trump's national security advisor/

National Security Adviser H.R. McMaster attends a meeting between President Donald Trump and Crown Prince Mohammed bin Salman of the Kingdom of Saudi Arabia in the Oval Office at the White House on March 20, 2018 in Washington, D.C.

Credit: Pool

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Credit: Pool