WASHINGTON — President Donald Trump announced Tuesday on Twitter that he has "terminated" top U.S. cybersecurity official Christopher Krebs.
In a pair of tweets, Trump said that Krebs gave a "highly inaccurate" statement about the security of the 2020 presidential election.
Trump, who has not yet conceded to president-elect Joe Biden, alleged that the election was riddled with "massive improprieties and fraud." Twitter labeled the president's tweets with a warning citing the claim about election fraud is disputed.
Krebs, who heads the Department of Homeland Security's Cybersecurity and Infrastructure Security Agency, is responsible for leading the effort to protect U.S. elections. He has previously said that there is no evidence the elections were compromised by foreign interference.
On Election Day, Krebs called on Americans to be patient and "to treat all sensational and unverified claims with skepticism."
"Regardless of the outcome here, there is a common bond that is stronger than political affiliation and that is that we are all Americans," Krebs said during a Nov. 3 press conference, adding, "keep calm and vote on, and after today, keep calm and let them count on."
Earlier on Tuesday, Krebs tweeted from his government account, "On allegations that election systems were manipulated, 59 election security experts all agree, in every case of which we are aware, these claims either have been unsubstantiated or are technically incoherent."
Less than an hour after Trump tweeted about his firing, Krebs tweeted from his personal Twitter account: "Honored to serve. We did it right."
He is the latest Trump administration official to depart on the heels of the election.
"I'm proud of the work we did at CISA," Krebs told NBC News on Tuesday night after the firing. "I'm proud of the teammates I had at CISA. We did it right."
A source with knowledge of the firing told NBC News Krebs found out the news via Twitter and that it was upsetting for him because he took the work seriously.
Several sources close to Krebs told NBC News in recent days that it was a matter of "when, not if" Krebs would be fired. They expected him to continue to push back on the president's misinformation about the election to the end and not "lay low."
"He's been on death watch," said a person close to Krebs.
"Chris Krebs is an extraordinary public servant and exactly the person Americans want protecting the security of our elections," Mark Warner (D-Va.), vice chairman of the Senate Select Committee on Intelligence, said in a statement. "It speaks volumes that the president chose to fire him simply for telling the truth."
Last week, Trump fired Defense Secretary Mark Esper via Twitter and replaced him with Christopher Miller, director of the National Counterterrorism Center.
On the heels of Esper's removal, a Trump administration official told CNBC's Eamon Javers that "I assume FBI and CIA are next," referring to FBI Director Christopher Wray and CIA Director Gina Haspel.
The Department of Homeland Security did not immediately respond to a request for comment.
The latest revelation comes as Trump has rejected the results of the U.S. presidential election. Other top administration officials, such as Vice President Mike Pence and Secretary of State Mike Pompeo, have publicly insisted that the election is not over.
—NBC News contributed to this report