Flynn flipped and the US markets plunged.
But it wasn't the charge and guilty plea over lying to the FBI.
It was because the potential significance of what President Trump's former national security adviser Michael Flynn was offering as part of his deal became clear.
In a court document prosecutors said that Mr Flynn had been directed by senior members of the presidential transition team as he conducted conversations with the Russian ambassador about Moscow's response to US sanctions.
ABC News even reported, citing a confidante of Mr Flynn, that the retired 3-star general was prepared to testify that Donald Trump himself directed him to make contact with the Russians.
And just like that, the scandal strode right up to the Oval Office and knocked firmly on the door.
Under US law, incoming administrations, essentially viewed as a collection of private citizens until sworn in to office, cannot conduct foreign policy.
Apart from anything else, such testimony would directly contradict the repeated insistence that no-one in the president-elect's transition team contacted or worked with the Russians.
A number of those team members have presumably said the same thing to Department Of Justice investigators interviewing them as part of the Russia probe.
It would also cast Mr Trump's early defence of Mr Flynn and his alleged request to former FBI director James Comey to go easy on him, in a less than optimal light.
Since then the White House's talking points have morphed, and you will hear them as long as the Mueller investigation continues.
- "Flynn also worked for the Obama administration." Yes, but he was sacked and Barack Obama subsequently warned Mr Trump not to hire him.
"Flynn wasn't influential." He was in the administration for 25 days, but national security adviser is still one of the most senior roles in government.
"Flynn was acting alone." Prosecutors have just told a court they are confident of making a case to the contrary.
More from Donald Trump
- "Flynn is a proven liar, so no-one should be surprised." It is not the admission of lying, but what he is offering as part of the deal that is significant here.
- "He's implicated no one but himself." See above.
Make no mistake, the White House is running out of ways to insulate itself from Michael Flynn.
Whatever he tweets or says next, President Donald Trump must know it.