US President Donald Trump has sacked Rex Tillerson as secretary of state, he announced in a tweet on Tuesday. He said that former CIA chief Mike Pompeo will be his replacement. Pompeo is to be replaced by Gina Haspel, his deputy at the CIA, Trump tweeted. She would be the first woman in that role. "Mike Pompeo, Director of the CIA, will become our new Secretary of State. He will do a fantastic job! Thank you to Rex Tillerson for his service! Gina Haspel will become the new Director of the CIA, and the first woman so chosen. Congratulations to all!" Trump said on Twitter. A White House official said Trump wanted to have a new team in place ahead of upcoming talks with North Korea and various trade talks. The official spoke on condition of anonymity because the official was not authorized to speak publicly. There had been longstanding rumors throughout most of Tillersons tenure of friction between Trump and his secretary of state, a former Exxon Mobile Corp. CEO. Tillerson had just returned from a shortened trip to Africa hours before Trumps announcement. Trump offered no explanation for the change. The resignation represents the biggest shakeup of the Trump cabinet so far and had been expected since last October when reports surfaced about a falling out between Trump and Tillerson, 65, who left his position as chief executive of Exxon Mobil to join the administration. Trump publicly undercut Tillersons diplomatic initiatives numerous times, including on Monday when the former secretary of states comments about Russia appeared to be at odds with those of the White House. Tillerson also appeared out of the loop last week when Trump announced he would meet with North Koreas leader and become the first sitting US president to do so.