Tillerson warns Russia and snubs Trump in an emotional farewell speech.

Rex Tillerson seemed visibly shaken in his impromptu farewell speech on Tuesday (March 13), hours after news broke that the now-former US secretary of state had been fired by Donald Trump.

The State Department was unaware of the reasons for Tillerson's firing, an official there said Tuesday morning. But the announcement came a day after Tillerson contradicted the White House about the recent poisoning of a British spy, saying it "clearly" came from Russia—a position disputed by the Trump administration.

.@ABC NEWS SPECIAL REPORT: Sec. Rex Tillerson gives remarks after Pres. Trump announced his replacement on Twitter this morning.https://t.co/6jBbqVIe0K

— ABC News (@ABC) March 13, 2018

In his speech, Tillerson never thanked the president, and only mentioned him once, saying, "I received a call today from the president of the United States a little after noon time from Air Force One." That's about three hours after Trump tweeted that CIA director Mike Pompeo would replace Tillerson as secretary of state.

Tillerson also said that "much work remains to respond to the troubling behavior and actions on the part of the Russian government," and warned that Russia could face "greater isolation on their part, a situation which is not in anyone’s interest.”

He praised the State Department, which has lost decades of expertise under his tenure as waves of career officials departed. "The world needs selfless leaders like these ready to work with longstanding allies," Tillerson said. He closed with praise for his fellow Americans, citing their “devotion to a free and open society,” “acts of kindness to one another,” honesty, and “quiet hard work." Tillerson's last day at the State Department is March 31.