We know the FBI made some serious mistakes in the Russia investigation. The misstatements and omissions by FBI officials in their applications for surveillance of Trump campaign aide Carter Page were egregious. The recent disclosures about how they prepared to question Flynn in 2017 should trouble anyone who worries about abuse of power by federal investigators seeking damning information from a suspect.

But none of that addresses the fundamental question that got this story rolling in the first place: Why was the incoming national security adviser telling the Kremlin’s man in Washington not to worry about the expulsion of 35 of his spies, because when the new administration took office, “we’ll review everything”?

That was the wrong message to be sending in December 2016. And with the accumulation of evidence since then about the scope of Russian subversion, it’s even more troubling.