File photo taken on Nov. 2, 2017 shows H.R. McMaster speaks at a press briefing at the White House in Washington D.C., the United States. U.S. President Donald Trump tweeted on March 22, 2018 that John Bolton, former U.S. Ambassador to the United Nations, will replace General H.R. McMaster to be his new national security adviser. (Xinhua/Yin Bogu)