Just a few hours before he was sacked, Krebs took to Twitter to rebut Trump and other Republicans' claims that election infrastructure was tampered with noting the claims either have been unsubstantiated or are technically incoherent.
In response President Trump opted for his favoured policy for dealing with anyone who disagrees with him.
Mr Krebs retweeted a Twitter post by an election law expert that said: "Please don't retweet wild and baseless claims about voting machines, even if they're made by the president".
In another tweet, Trump alleged that in Detroit, there are "FAR MORE VOTES THAN PEOPLE".
Republican senator Richard Burr, who until recently was chairman of the same committee, said Krebs and his team "worked diligently to strengthen our election infrastructure, helping to shore up vulnerabilities and build trust between State and Federal Governments".
Mr. Krebs has led the CISA since it was formed two years ago.
And the president insisted that MI could no longer certify the election result, repeating allegations that more votes were counted in Wayne County than there were eligible voters. Both of Trump's tweets were flagged by the microblogging site.
Responding to his termination, Krebs stated on Twitter: "Honored to serve". Defend Today, Secure Tomrorow.
And his firing drew reaction from other senior officials, both in the USA and in the UK.
Christopher Krebs will have the last laugh.
"He's done everything you would want a senior official at D.H.S.to do", Chertoff told the Times. Ben Sasse said Krebs "did a really good job" and that "he obviously should not be fired".