Deputy Attorney General Rod J. Rosenstein appears at the Global Cyber Security Summit in London this month. (Mary Turner/Reuters)

Deputy Attorney General Rod J. Rosenstein is in charge of overseeing special counsel Robert S. Mueller III's investigation into Russian interference in the 2016 election. The U.S. intelligence community has said explicitly that it has no opinion on whether Russian interference affected the election.

But Rosenstein does — at least when it comes to the ads for which Russia paid.

Appearing on the “Target USA” podcast from Washington's WTOP radio station, Rosenstein said he thought American voters were too “savvy” to be influenced by such ads.

Here's the full quote, in context:

I think what people need to keep in mind is that there’s a distinction between people trying to sway American elections and succeeding in swaying American elections. I think one of our responsibilities is to make sure that people understand, you know, what the risks are, but also that they make their own determinations. You know, American citizens are pretty savvy, and they decide who to vote for. I don’t think they’d be influenced by ads posted by foreign governments. I think people are more thoughtful about that in the way that they make their decisions. But, nonetheless, you know, if we have foreign countries that are seeking to interfere in our elections, I think we need to take appropriate action in response.

I'm skeptical of this argument.

We have just come off an election in which conspiracy theories and fake news ran through social media like viruses. And we all have that relative who passes along a dubiously spun news report claiming the other party's politician said something that they didn't really say. People are unable to distinguish fact from fiction in these cases, but they know when they are being influenced by an ad that might have been paid for by a foreign entity (and which they likely don't even realize came from a foreign entity)?

As The Post reported a month ago, the 3,000 Russian-purchased Facebook ads that the social media giant turned over to Congress show “a deep understanding of social divides in American society, with some ads promoting African American rights groups, including Black Lives Matter, and others suggesting that these same groups pose a rising political threat.” In other words, they appeared to be relatively sophisticated and focused on issues that arouse Americans' passions.

To suggest that Americans, as a whole, are too smart to be influenced by such ads is giving them a lot more credit than most political scientists — or journalists or political activists — would give them. That's not to say that people are stupid, but oftentimes we don't realize the factors that are influencing us. And, to put it diplomatically, there are certainly less-sophisticated consumers of political news out there. Look no further than all the people who bought into the birther conspiracy theory.

The other question is why Rosenstein felt the need to offer this theory. The question wasn't really about that — it was about whether Russia is interfering with anything besides American elections — and Rosenstein seemed to volunteer this idea about how Russia's ads didn't work.

The question of whether Russian interference actually mattered in the 2016 election wouldn't seem strictly pertinent to the investigation that Rosenstein is overseeing, so it's not as if this necessarily jeopardizes his independence. It's also completely unknowable whether Russia changed the result of the 2016 presidential race.

But if there is one person who'll be glad to see these comments, it's President Trump, who has incorrectly stated that the intelligence community concluded Russia didn't affect the election. Trump has a real interest in downplaying Russia's success in interfering, because the idea that it did matter risks undermining his legitimacy as president.

Whether it was his intention, Rosenstein's comments seem to bolster Trump's argument — at least in one, limited case. And it's totally unclear why he even went there.