But here’s the essential point. Even if Kilimnik’s evidence-free statement that Ukraine hacked the DNC was a crucial seed of today’s toxic conspiracy theory (which seems unlikely), and even if some Russian handler instructed him to place that seed into Manafort’s mind (which is unproven), then alt-right amateur sleuths, American conspiracy theorists, Trump aides, and his unswerving congressional backers had to circumnavigate a large and growing mountain of hard evidence that implicated Russian intelligence in the 2016 active-measures campaign. They had to come up with ever more twisted ways to explain that evidence away. And they had to work tirelessly to spread their alternative theories.

American conservatives and elected officials are not passive, remote-controlled dummies that can be swayed with one distant statement or obscure social-media post—and thus absolved of responsibility for peddling and improving on outlandish conspiracy theories. Blaming domestic ills on foreign interference is a temptation that befits weakening democracies.

Again, perhaps American intelligence agencies have solid evidence that Russia had a pivotal role in developing the Ukraine conspiracy theories. If so, they need to deliver the goods, and show at least some of this evidence to Americans in an official public statement. Countering disinformation with, in effect, more disinformation is counterproductive, even dangerous; indeed, it is not too dramatic to say that this tendency plays right into the Kremlin’s hands.