Conservative opponents see Bolton as an establishment guy and interventionist- having served in two Bush administrations-a member of the swamp they wish to drain. "Iraq was a waste of blood and treasure".
The John Bolton Super PAC, led by the former diplomat and foreign policy hard-liner, paid Cambridge Analytica more than $1.1 million in the 2014 and 2016 cycles for research, according to Federal Election Commission filings.
Just last Friday, senior White House officials assured reporters McMaster would not be fired.
The move, which was sudden but not unexpected, signals a more confrontational approach in American foreign policy at a time when the United States president faces mounting challenges, including from Iran and North Korea, the New York Times commented.
"The risks of a war with Iran or North Korea are now significantly greater than they were this morning", he says.
Deputy Minister and former Israeli ambassador to the US Michael Oren said, "Bolton's appointment sends an unequivocal message to Iran that the days of the bad nuclear agreement are coming to an end".
President Donald Trump's surprise announcement Thursday to replace his national security adviser H.R. McMaster with John Bolton is not only part of a broader shakeup but represents a shift toward an increasingly hawkish foreign policy posture as he faces major decisions within weeks on North Korea and Iran.
"Given the gaps in USA intelligence about North Korea, we should not wait until the very last minute".
Only recently, he threw verbal cold water on President Trump's decision to meet with North Korean dictator Kim Jong-un in late May, calling it "diplomatic shock and awe" and advising such a meeting be short and to the point.
Earlier this year he appeared to oppose such talks happening at all.
Bolton served as US Permanent Representative to the United Nations from 2005-2006 and as Under Secretary of State for Arms Control and International Security from 2001-2005.
"This deal needs to be abrogated and America must craft a new reality that reflects the actions of the Iranian regime", he wrote.
CNN also confirmed that Bolton met with Trump Thursday. Yet, if Bolton's views on many issues align with those of the president, they are not in ideal sync.
When the Cold War ended, the U.S. no longer faced a credible challenger to its military supremacy, and talks of pre-emptive military action were mostly shut down.
Trump's first national security adviser, Michael Flynn, was sacked for lying about contacts with the Russian embassy and has since pleaded guilty for making false statements to the Federal Bureau of Investigation.
If there were ever any checks on the erratic, impulsive Trump foreign policy, they almost vanished last week.
Back in 1994 he was quoted saying the U.S. was the world's "only real power".
"Yes, John Bolton really is that risky", wrote an alarmed New York Times editorial board.
The Pentagon said it does not have an official comment to make at this time. He resigned after serving 17 months as a Bush "recess appointment", which allowed him to hold the job on a temporary basis without Senate confirmation.
The US Vice President Mike Pence has described Bolton as a "highly respected American patriot".
Bolton's executive wrath is said to be directed primarily at those who were brought in during the Obama administration.
But critics on both sides of politics have slammed the appointment.
After his appointment, Bolton tried to distance himself from his past statements.
"You just hired someone who is likely to start another wasteful war!", tweeted another.