It is impossible to overstate the significance of the revelation that the FBI is investigating possible collusion between the Russian government and President Donald Trump's campaign team during last year's election.
This bombshell could eventually be remembered as the beginning of the end of the chaotic Trump presidency. At the very least, it means Mr. Trump will not soon escape from under the cloud of suspicion hovering over him and his campaign team.
FBI Director James Comey confirmed the ongoing investigation on the first day of a congressional hearing into Russia's well-established meddling in the U.S. election, and into its efforts to rig the outcome in Mr. Trump's favour.
To add insult to injury, Mr. Comey, along with Michael Rogers, the Director of the National Security Agency, also contradicted Mr. Trump's wildly irresponsible claims on Twitter that former president Barack Obama had ordered the wiretapping of Trump Tower in New York City during the election campaign.
"We have no information to support those tweets," Mr. Comey said, in a comment that must be the first of its kind regarding a sitting President.
You could see the extent of the damage to Mr. Trump in his flailing response. His staff immediately tweeted on his presidential Twitter account that "the NSA and FBI tell Congress that Russia did not influence electoral process" – an utterly false statement directly rebutted by Mr. Comey and Mr. Rogers later in their hours-long testimony.
Mr. Trump's press secretary, Sean Spicer, tried a variety of different dodges. He disingenuously downplayed the roles of key campaign officials who had known ties to Russia. And he insisted that people were naive to think any wrongdoing might have occurred just because the FBI was involved.
"There's an assumption that, because there's an investigation, it must be about something," said Mr. Spicer.
Yes, it is indeed true that it would be unfair to shout "Lock him up!" based on an incomplete FBI investigation – just ask Hillary Clinton if you'd like to know exactly how unfair.
But fairness has little to do with it. Mr. Trump now finds himself in a scandal that has raised some of the most troubling questions about a sitting American president in decades. He will not be able to tweet his way out of it.