President Trump has a new national security adviser -- John Bolton. The former United Nations ambassador and arms control official started work Monday, replacing HR McMaster. Bolton is known for his extreme views on Iran, and the DPRK. CGTN's Nathan King takes a look at the man and his ideas.

Despite a number of years in the public eye, John Bolton has only held high office once before - temporarily as the U.S. ambassador to the United Nations under President George W. Bush. He was in that position for less than a year and a half but never confirmed by the U.S. Senate as he was considered too controversial.

But Bolton has been a fixture as an analyst on Trump's favorite TV channel, Fox News, where he has been espousing his hawkish views for years.

SOUND MONTAGE OF STRONG STATEMENTS "in Iran The only diplomatic option left is to end the regime in North Korea by effectively having the South take it over. The regime needs to change. I think the world with clarity."

Bolton believes in the preeminence of the U.S. in world affairs and American exceptionalism. He often pushes unilateral military solutions to solve the thorniest of diplomatic problems. He supported the U.S. invasion of Iraq before and after.

When it comes to today's global issues, he is no less bombastic.

He wrote this opinion piece less than two months ago in the Wall Street Journal entitled "The Legal Case for Striking North Korea First." He wrote in part:"Pre-emption opponents argue that action is not justified because Pyongyang does not constitute an "imminent threat." They are wrong."

In the lead up to the Iran nuclear deal in 2015, he wrote this New York Times opinion piece with the headline "To Stop Iran's Bomb, Bomb Iran." In it, he advocated Israeli or U.S. attacks against Iran's nuclear fuel installations and called for the overthrow of the government in Tehran - writing in part: "Such action should be combined with vigorous American support for Iran's opposition, aimed at regime change in Tehran."

Bolton has strong views on Taiwan too- backing more military sales to the island, diplomatic contacts and U.S. port calls- he has encouraged independence.

The big question now is will John Bolton's views become U.S. policy.

TRUMP: You are going to do a fantastic job and I appreciate you joining us.

BOLTON: Thank you, it's an honor to be here.

Trump has been listening to Bolton for a long time. He was reportedly on the short list for U.S. secretary of state before Rex Tillerson.

NATHAN KING WASHINGTON "The extent of John Bolton's influence on President Trump will be known soon- Next month, the White House has to decide whether to scrap or stay in the Iran nuclear deal. The U.S. is also planning a high stakes summit with DPRK leader Kim Jong Un later this year. And as John Bolton takes up his new job, the U.S. is mulling over its response to another alleged chemical weapons attack in Syria and a potential trade war with China. Lots of diplomacy needed from a national security adviser in his first days on the job. Nathan King, CGTN, at the White House."