“The work you see now from Facebook, Microsoft and others to be more proactive is a trend that is positive — it’s part of the solution, and I would want to see that trend continue,” said Graham Brookie, director of the Digital Forensic Research Lab at the Atlantic Council, a think tank that has been working with Facebook on election-security issues.

But Mr. Brookie added: “Is this a solution? No, definitely not.”

A solution, he said, would involve a society-wide reckoning with the problem of the vulnerabilities that the internet has uncovered in democratic society. A solution would involve the federal government taking the lead in such an effort, which is not really happening at the moment. A solution would also involve citizens becoming far more vigilant about what they see online, how they respond to it, and the effect it has on their political lives.

And even with all that, we may not really get an actual solution. Instead, the best we might hope for is something like an ongoing cat-and-mouse game between good and bad actors online: a fight that never ends, but whose damage we can at least hope to reduce.

That’s the long game. The short game is rather more depressing.

Consider the most pressing question: How confident should you be that the coming midterm elections will be safe from hacking and propaganda operations online? The most likely answer: Nobody knows for sure, but probably not very confident.

Facebook and other tech companies are stepping up their efforts to police their sites before the midterms. But some of the threats they have spotted so far have little to do with the election. The Iranian operation, for example, has been going on for years, and to judge by some of the content posted by these Facebook pages, was not aimed squarely at American elections, but instead American policy.

In a call with reporters on Tuesday, Mr. Zuckerberg argued that Facebook has been making progress on keeping elections safe, having learned from several races around the world since 2016.

“There was the French election, the German election, the Alabama special election, the Mexican election — and in each of these elections, our systems have been able to find a lot of fake accounts that were attempting potentially to do bad things on the system,” he said.