"We disagreed on things", Trump said moments later, a diplomatic version of a hard relationship with his top diplomat that included reports that Tillerson had called the president a moron in meetings with other officials.
"I felt like, look, I just need to get back", Mr Tillerson told reporters on his plane home, reports the Washington Post. "When you look at the Iran deal, I think it's bad and he thinks it's okay", Trump said.
Trump mentioned differences over how to handle the Iran agreement, which he wanted to withdraw from. "So we were not thinking the same". It is a surprising one, however: Tillerson had survived months of antagonism from President Trump, and there was no particular reason to think that this was the moment when the ax would fall.
Pompeo's alignment with Trump and outspokenness on sensitive policy issues raised questions among current and former CIA staffers who questioned whether the agency's director was pursuing policies and making recommendations that would please the White House, former intelligence officers say.
White House press secretary Sarah Huckabee Sanders said on Monday the White House was standing with the United Kingdom as it investigated the attack, but she stopped short of blaming Russian Federation for the attack. Top economic adviser Gary Cohn announced his resignation last week, not long after communications director Hope Hicks and staff secretary Rob Porter both departed near the start of Trump's second year in office.
Mr Trump offered no explanation for the change. When Trump ultimately accepted Kim's invitation for a meeting, Tillerson was in Ethiopia, though he said he spoke with Trump about it shortly before it was announced.
According to the White House, Gina Haspel, the Deputy Director of the Central Intelligence Agency, will be nominated to replace Director Pompeo.
If confirmed by the U.S. Senate, Pompeo also would take over a State Department shaken by the departures of many senior diplomats and embittered by proposed budget cuts. "He will do a fantastic job!" the president tweeted.
Trump's early morning announcement took the State Department by surprise, barely four hours after Tillerson returned prematurely from a trip to Africa and just as officials had been preparing yet again to dispute rumors of his demise.
The circumstances behind the firing were unclear.
A government outsider lacking diplomatic experience, Tillerson arrived at the White House after decades at Exxon Mobile, rising from engineer in 1975 to chairman and CEO in 2006, overseeing vast expansion of the company's operations worldwide.
A top State Department official says President Donald Trump never explained to ousted Secretary of State Rex Tillerson the reason why he was sacked.
Under Secretary Steve Goldstein said: "The Secretary had every intention of staying because of the critical progress made in national security".
Haspel, who has extensive overseas experience, briefly ran a secret CIA prison where terror suspects Abu Zubayadah and Abd al Rahim al-Nashiri were waterboarded in 2002, according to current and former US intelligence officials who spoke to The Associated Press on condition of anonymity. Tillerson also told reporters that the attack would "certainly trigger a response".
While Tillerson has been critical of Russia's interference in the 2016 presidential campaign and its intervention from Ukraine to Syria, Pompeo has at times bolstered Trump's view that inquiries into Russian election meddling is a "witch hunt" meant to undercut his presidency.
The official said Trump wanted Pompeo in place before the US president's planned talks with North Korean leader Kim Jong Un and trade negotiations.
The officials weren't authorized to speak publicly and demanded anonymity.