"This has been the honor of a lifetime and I am grateful to the president and the secretary for this opportunity. I look forward to getting some rest," Undersecretary of State Steve Goldstein told AFP.
No reason was given for the decision, but earlier Goldstein -- who was undersecretary for public affairs and public diplomacy -- had told reporters that Tillerson was not expecting to be ousted.
Goldstein's dismissal must also have been at short notice, as he had been due to brief reporters within an hour of the announcement.
Afterwards, Goldstein first tweeted and then issued a statement declaring that Trump had not called Tillerson prior to the announcement and that the secretary was "unaware" of the reasons for his departure.
"The secretary had every intention of remaining because of the tangible progress made on critical national security issues. He established and enjoyed relationships with his counterparts," he said.
Trump, by contrast, had portrayed the decision as somewhat mutual and long in the making, saying: "Rex and I have been talking about this for a long time.
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