The US President Donald Trump said on Tuesday that he dismissed Rex Tillerson as secretary of state at least in part over policy differences.

The two had disagreed over critical foreign policy issues, including the Iran nuclear deal.

Tillerson has repeatedly had to deny falling out with the president - including that he called him a "moron". He is urging a smooth transition - after his dismissal by Trump, via Twitter.

The outgoing secretary of state will be replaced by CIA director, Mike Pompeo.

Al Jazeera's Rosiland Jordan looks back at the friction between Tillerson and Trump.