Who is John Bolton？ Trump's National Security Adviser, just fired

President Donald Trump announced he had fired his National Security Adviser John Bolton after reports that he and Bolton disagreed over a controversial plan to host the Taliban for negotiations.

Over the years, Bolton has held some controversial stances, including advocating for preemptive military strikes on North Korea and Iran, and regime change in the latter.

As an undersecretary in the State Department during the George W. Bush administration, Bolton also pushed the now-discredited belief that Iraq was in possession of weapons of mass destruction.

Here's how Bolton went from being a mid-level bureaucrat in the Reagan administration to the most important person directing US national security policy.

President Donald Trump abruptly announced in a Tuesday tweet he had fired his National Security Adviser John Bolton because Trump “disagreed strongly with many of his suggestions.”

Bolton's abrupt firing came after reports that Trump and Bolton, a long-time war hawk, disagreed over a controversial plan to host the Taliban for negotiations to end the war in Afghanistan at Camp David.

Bolton, a graduate of Yale law school, began working on foreign policy and national security issues under the Reagan administration in the early 1980s, where he quickly developed a reputation as a defense hawk skeptical of the US bureaucracy and international institutions.

Over the years, Bolton has held some controversial stances, including advocating for preemptive military strikes on North Korea and Iran, regime change in the latter, and pushing Russia for harboring Edward Snowden.

Read more: Trump fires National Security Adviser John Bolton, saying he 'disagreed strongly with many of his suggestions'

As an undersecretary for arms control in the Bush administration, Bolton also pushed the now-discredited belief that Iraq was in possession of weapons of mass destruction which served as the justification for the US invasion of that country.

He later served as the US ambassador to the United Nations — an institution he routinely criticized as ineffectual — where he continued to push for sanctions on countries accused of possessing or developing nuclear weapons.

Bolton served as Trump's National Security Adviser for about 16 months, and pushed to fulfill his decades-long vision of the US engaging in a direct confrontation with Iran, according to a May profile of Bolton published in the New Yorker.

Here's how Bolton went from being a mid-level bureaucrat in the Reagan administration to the most important person directing US national security policy.