Rex Tillerson has fronted the media after being sacked as US Secretary of State by President Donald Trump.
Mr Trump has replaced Mr Tillerson with CIA director Mike Pompeo. He also nominated Gina Haspel to replace Mr Pompeo and become the first female director of the CIA.
At 7am (NZT) Mr Tillerson read a statement to the press, avoiding all mention of the nature of his firing.
"US leadership starts with diplomacy," he said.
"The rewarding thing about having leadership and partnership in place is you can actually get some things done."
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After thanking the State Department for "a few of their accomplishments", which included military and international relations, he spoke of the work still to be done.
"In other areas where much progress was made much work remains.
"There's more to be done [in Syria] in respect to achieving peace and stabilising Iraq.
"Much work remains to establish a clear view for the nature of our future relationship with China.
"Russia must assess carefully how it's acting in the best interests of the Russian people and of the world more broadly."
He then closed the brief appearance by thanking for "the privilege of serving".
"I'll now return to a private life as a private citizen."
The move represents the biggest shake-up of the Trump cabinet so far and had been expected since last October when reports surfaced about a falling out between Mr Trump and Mr Tillerson, 65, who left his position as Chief Executive of Exxon Mobil to join the administration.
Mr Trump publicly undercut Mr Tillerson's diplomatic initiatives numerous times, including on Monday (local time) when his comments about Russia appeared to be at odds with those of the White House.
Mr Tillerson also appeared out of the loop last week when Mr Trump announced he would meet with North Korea's leader and become the first sitting US president to do so.
In October, NBC news reported that Mr Tillerson called the president a "moron," something Mr Tillerson never actually denied.
On Tuesday Mr Trump cited differing opinions on policy and a "chemistry" problem between him and Mr Tillerson for his decision.
Speaking to reporters on the White House lawn Mr Trump said: "It was a different mindset, a different thinking. We got along actually quite well, but we disagreed on things.
"When you look at the Iran deal, I think it's terrible. I guess he thought it was okay.
"I wanted to either break it or do something and he felt a little bit differently, so we were not really thinking the same.
"Rex is a good man, I like him a lot and I wish him good things, but I think he will be happier now."
Earlier, on Twitter Mr Trump wrote: "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!"