There’s a critical back story to Russia’s interference: A longstanding Kremlin grudge against Mrs. Clinton, cemented in 2011 when, as secretary of state, she cast doubt on whether Russia’s parliamentary elections, plagued by allegations of fraud and vote rigging, had been “free and fair.”

The bulk of the Russian team’s online trolling efforts were directed at Mrs. Clinton, but the indictment notes that they also took aim at other, Republican candidates; Mr. Trump, Bernie Sanders and the Green Party candidate, Jill Stein, were spared. The trio had something more than opposition to Mrs. Clinton in common: A central theme of their campaigns was that the American political system is fundamentally rigged — the same claim that had so incensed Mr. Putin.

This same theme crops up in many of the Russian front groups’ attacks: “Hillary Clinton has already committed voter fraud during the Democrat Iowa caucus,” one social media post declared. One of the more memorable stunts the Russian team sponsored — hiring an American to attend rallies dressed as Mrs. Clinton in prison garb, toting an ersatz jail cell — fits the same pattern: She had to be cast not merely as an inferior candidate, but as a criminal who could win only through corruption.

Mr. Trump was vehemently committed to the same message, not only leading those infamous chants of “Lock her up!” but routinely declaring that if he were defeated — which polls throughout the campaign suggested was the most likely outcome — it would only be because Democrats had rigged the vote.

In hindsight, it’s natural to think that Russia’s primary aim was to achieve the upset Trump victory we now know occurred. But if they were relying on the same polls as the rest of the world, they would have regarded that as a long‐​shot. It seems at least as likely that they hoped a strong showing would position a defeated Mr. Trump as a thorn in Mrs. Clinton’s side, casting a pall over the legitimacy of her administration by fuming publicly about how he had been cheated. (They probably could not have imagined that Mr. Trump would do this even in victory, insisting without any evidence that he had lost the popular vote only because of voter fraud.)

If we run with the hypothesis that Russia’s core goal was to sow doubt about the integrity and fairness of American elections — and, by implication, erode the credibility of any criticism aimed at Russia’s — then the ultimate exposure of their interference may well have been viewed not as frustrating that aim but as one more perverse way of advancing it.

Similar logic might account for Russian cyberattacks on many state voter registration systems — first reported in June and more recently confirmed by Department of Homeland Security officials. There’s a consensus among cybersecurity experts that our unusually decentralized electoral system would make it extraordinarily difficult to surreptitiously change the result of a national election via hacking from abroad. But that might not be necessary: An attack might succeed just by creating widespread uncertainty about whether results had been altered, creating a crisis of legitimacy by the ultimate victor.

United States intelligence officials themselves have voiced suspicions that Russia intended to be caught. “They were unusually loud in their intervention,” James Comey, the former F.B.I. director, told Congress at a hearing last March. “It’s almost as if they didn’t care that we knew.” Wade into any online political discussion, where the conversation‐​ending accusation “Russian bot!” has become a commonplace, and it’s hard to deny that it’s worked.

If this sounds plausible, we should also consider that our political response, too, may have been part of the plan. With President Trump dutifully refusing to implement retaliatory sanctions imposed on Russia by a large bipartisan majority in Congress, legislators have begun eyeing the online platforms on which so much disinformation spread. “You created these platforms,” Senator Dianne Feinstein, Democrat of California, railed at a panel of lawyers for Google, Facebook and Twitter in November, “and now they’re being misused. And you have to be the ones who do something about it — or we will.”

That would be a final irony, and an unpleasant one. No less than our “meddling” in their internal elections, Russia has long resented United States criticism of the country’s repressive approach to online speech. Their use of online platforms to tamper with our presidential race reads not only as an attack, but as an implicit argument: “The freedoms you trumpet so loudly, your unwillingness to regulate political speech on the internet, your tolerance for anonymity — all these are weaknesses, which we’ll prove by exploiting them.”

Urgent as it is for the United States to take measures to prevent similar meddling in the next election, we should be careful that our response doesn’t constitute a tacit agreement.