Secretary of State Rex Tillerson spoke from the State Department Tuesday, hours after President Trump announced he would be replaced by CIA Director Mike Pompeo. 

“What is most important is to ensure an orderly and smooth transition during a time that the country continues to face significant policy and national security challenges," said Tillerson, declining to take questions.

He said Deputy Secretary John Sullivan will take over his responsibilities at the end of the day. Tillerson said he will remain at the State Department through the end of the month to oversee the transition to Pompeo, who must be confirmed by the Senate.

"I'll return to private life as a private citizen. As a proud American, I'm proud of the opportunity I had to serve my country. ... God bless America," he said.

Tillerson said he received a phone call from Trump around noon ET from Air Force One. The president spoke outside the White House Tuesday morning after tweeting the news of Tillerson's firing. 

"We got along actually quite well, but we disagreed on things,” Trump said of Tillerson. "When you look at the Iran deal, I think it's terrible. I guess he felt it was okay…So we were not really thinking the same."

The State Department said after the announcement that Tillerson was not aware of his firing before Trump's tweet.

Watch Tillerson's comments above.

Trump Explains Rex Tillerson's Firing, Will Speak to May on Poisoning of Ex-Russian Spy

Stirewalt on Tillerson's Ouster: Turns Out Trump Doesn't Like to Say 'You're Fired'