United States President Donald Trump fired Secretary of State Rex Tillerson on Tuesday and replaced him with CIA Director Mike Pompeo. The move comes after a series of public disagreements between the two on issues ranging from Russia to North Korea.

Tillerson will be the most senior departure from the Trump administration since he took office more than a year ago and comes amid talks of an unprecedented meeting with the leader of North Korea.

Trump tapped the CIA's deputy director, Gina Haspel, to replace Pompeo at the intelligence agency.

In July, Tillerson had reportedly called Trump a "moron" following the president's suggestion that the U.S. should increase its nuclear arsenal 10-fold. Following media reports, Tillerson refused to directly address whether he had made the comment, although a State Department spokeswoman later issued a denial.

Reuters quoted a senior White House official who said Trump asked Tillerson to step down on Friday but did not want to make it public while he was on a trip to Africa. Trump's announcement came only a few hours after Tillerson landed in Washington after a trip that had been cut short.

Tillerson had no diplomatic or political experience before becoming secretary of state. He appeared out of the loop last week when Trump announced he would meet with North Korea's Kim.

@realDonaldTrump 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!

"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.

Tillerson joined a long list of senior officials who have either resigned or been fired since Trump took office in January 2017. Others include strategist Steve Bannon, national security adviser Michael Flynn, FBI Director James Comey, White House chief of staff Reince Priebus, health secretary Tom Price, communications directors Hope Hicks and Anthony Scaramucci, economic adviser Gary Cohn and press secretary Sean Spicer.