Who is John Bolton, H.R. McMaster’s replacement?

On Thursday, President Donald Trump named John Bolton as his new national security adviser.

Bolton, former U.S. ambassador to the United Nations, was tapped to replace H.R. McMaster.

Bolton, 69, has a long history of work in Washington D.C., including leadership roles at the State and Justice departments and the U.S. Agency for International Development.

McMaster replaced Retired Army Gen. Michael Flynn after Flynn was fired 24 days into the Trump administration. Last, fall Flynn pleaded guilty to lying to investigators in special counsel Robert Mueller's probe into possible collusion between Trump's campaign and Russian officials during the 2016 presidential campaign.

Bolton will take over the job on April 9.

Here are a few things to know about Bolton:

• Bolton, a strong supporter of American military might, served in the administrations of Ronald Reagan, George H.W. Bush and George W. Bush.
• He was one of President George W. Bush's lawyers during the Florida vote recount in the 2000 presidential election.
• From 1985–1989, he was the assistant attorney general at the Justice Department.
• From 1989–1993, he was the assistant secretary for International Organization Affairs at the State Department.
• In May 2001, Bolton was named the under secretary of State for Arms Control and International Security.
• Between 1999 and 2001, he served on the board of the Committee for International Religious Freedom.
• Bolton served as United States Ambassador to the United Nations under George W. Bush. However, Senate Democrats and some Republicans blocked his nomination in 2005. He became ambassador by recess appointment from Bush.
• Bolton is considered a "super" hawk by some in Washington. According to a profile from Reuters, he kept a defused hand grenade on his desk during his time at the State Department.
• He recently wrote a commentary piece in the Wall Street Journal titled, "The legal case for striking North Korea first."
• He considered running for president in the 2012 election.
• In a December 2012 interview with Greta Van Susteren, he said Hillary Clinton faked a concussion so she would not have to testifying before Congress about the attack on the U.S. consulate in Benghazi, Libya.
• Bolton was senior vice president for public policy research at the American Enterprise Institute. The AEI is a public policy research institute.
• He has been a Fox News contributor.
• He's written several books including "Surrender is not an Option," and "How Barack Obama is Endangering Our National Sovereignty."
• Donald Trump considered Bolton for his Secretary of State
• He was interviewed for the job of national security adviser after Flynn was fired.