Bolton was a well-known man who had never encountered a war he did not like (except Vietnam, which he avoided). And the conflict with Iran is the war he seems to want most.
In his latest appearance at a MEK meeting, in 2018, Bolton declared: "The behavior and goals of the [Iranian] regime will not change and, therefore, the only solution is to change the regime itself. "
He has previously advocated for regime change in Venezuela, Iraq, North Korea, Libya and Syria, to name a few. critics of the 2015 Iran nuclear deal. He took the position of National Security Advisor in April 2018 and, a month later, the US unilaterally upheld the agreement.
With Bolton's departure, the Iranian hawk's mantle is now passed to Secretary of State Mike Pompeo. But, unlike Bolton, Pompeo seems to have prioritized his relationship with President Trump.
Bolton's departure may change Trump's stance on Iran, but perhaps not the substance.
Washington's "maximum pressure" policy was designed, according to Pompeo, to change Tehran's behavior. But with the severity of the sanctions, they appear to be designed to bring Iran to its knees.
Outside Bolton, such a meeting can now proceed without much resistance within the Trump White House.
Without sanctions relief, or its promise, Iranians are unlikely to play like Kim.
Also mitigating against a dramatic shift in US-Iran policy was Israeli Prime Minister Benjamin Netanyahu, who lobbied a succession of American administrations to do more tough stand in Tehran.