The president made the announcement via Twitter late Tuesday, amidst an ongoing flood of tweets about a rigged election. The president's ongoing claims of "widespread voter fraud" have been disputed by a majority of state and local election officials.
Krebs came into conflict with the president via his comments that the 2020 election has been secure and free of interference.
"The recent statement by Chris Krebs on the security of the 2020 Election was highly inaccurate, in that there were massive improprieties and fraud - including dead people voting, Poll Watchers not allowed into polling locations, “glitches” in the voting machines which changed votes from Trump to Biden, late voting, and many more," Trump tweeted.
...votes from Trump to Biden, late voting, and many more. Therefore, effective immediately, Chris Krebs has been terminated as Director of the Cybersecurity and Infrastructure Security Agency. — Donald J. Trump (@realDonaldTrump) November 18, 2020
Rumor Control: I never claimed there wasn’t fraud in the election, bc that’s not CISA’s job - it’s a law enforcement matter. We did provide info on measures elec officials use to prevent and detect dead voters, tho. Don’t buy it. And think 2x before sharing. — Chris Krebs (@C_C_Krebs) November 18, 2020
Krebs, who formerly worked at Microsoft for three years on cybersecurity policy, has been with the Department of Homeland Security since 2017, when CISA's predecessor, the National Protection and Programs Protectorate (NPPD), was still the highest cyberfocused risk management office in the federal government.