Washington DC (CNN) As election results were rolling in Tuesday night, an obscure website, consisting of only a single page, made a remarkable claim: Russia had used social media to interfere in the 2018 midterm elections.

The website, which had only emerged a few days earlier, claimed to be run by the Internet Research Agency (IRA), the Russian government-linked troll group indicted by Special Counsel Robert Mueller for allegedly interfering in the 2016 U.S. presidential election.

This wasn't the first time the person or people behind the site had sought attention. Over the weekend, they had reached out to a number of U.S. reporters who cover online disinformation, including me.

At that point, though, there wasn't much to report — just a random, anonymous website making wild claims about the Russian group outsmarting the American intelligence community and Silicon Valley and their efforts to prevent a repeat of 2016, when the trolls successfully posed as Americans on social media in an effort to sow chaos and discord.

Then on Monday night, Facebook announced that, acting on a tip from the FBI, it had taken down a network of Facebook and Instagram accounts due to concerns that they were tied to the IRA.

Facebook didn't disclose what accounts it had taken down. Only the FBI, Facebook, and the people behind the pages themselves should have known what they were.

But on Tuesday night, that odd website posted a list of Instagram accounts that it said included some of those which had been taken down — and it got the list right

"This evening a website claiming to be associated with the IRA published a list of Instagram accounts they claim to have created. We had already blocked most of these accounts yesterday, and have now blocked the rest," Nathaniel Gleicher, Facebook's head of cyber security policy, said in a statement late on Tuesday night.

The 2018 midterm election was in some ways a test for American intelligence and for tech companies like Facebook, Twitter and Google. They had failed to stop Russian meddling in 2016, but promised to do better in 2018 and 2020 and beyond. Until Election Day, with some exceptions, it seemed that they had indeed done better.

But the website and the boasts it contains raise new questions about that. Was there in fact a successful Russian meddling campaign going on under everyone's noses? Or were these empty boasts, bluster meant to cover up for a lack of impact this time around and make the IRA seem more effective than it is? If it is bluster, was the IRA ineffective in this election because it was stymied, or because it didn't try? Is this website and network even really the work of the IRA?

Some of the accounts were designed to appeal to activists on the left; some looked like they were run by supporters of Donald Trump. Others weren't political at all: There were fan accounts for Rihanna, Kid Rock, Kendrick Lamar and a porn actress, for instance. The IRA has previously used a similar tactic, running a network of seemingly innocuous accounts, often about pop culture, to build up an audience, before eventually exposing that audience to divisive political content.

On the other hand, though their content may have been relatively innocuous, some of the accounts had tens of thousands of followers and had been running for more than a year.

CNN reviewed archived versions of the accounts, and saw no material explicitly about the midterm elections, but CNN was unable to review all of the accounts' posts because of the removals.

The website that posted the list of the accounts proclaimed, "Citizens of the United States of America! Your intelligence agencies are powerless."

"Despite all their efforts, we have thousands of accounts registered on Facebook, Twitter and Reddit spreading political propaganda," they claimed, adding, "Hundreds of your fellow citizens are our unintentional agents unaware of the fact that they actually act for the good of the Russian 'troll farm.'"

If the message is indeed from the group, it is its most brazen attempt at claiming responsibility for a misinformation operation in the U.S.

Facebook's statement on Tuesday night hinted that the group was indeed the IRA. CNN has not independently confirmed this. The FBI, which Facebook has said provided the tip that led to the accounts, did not comment when contacted by CNN on Tuesday night.

But a statement that the FBI released with other intelligence and law enforcement agencies on Monday warned, "Americans should be aware that foreign actors -- and Russia in particular -- continue to try to influence public sentiment and voter perceptions through actions intended to sow discord. They can do this by spreading false information about political processes and candidates, lying about their own interference activities, disseminating propaganda on social media, and through other tactics."

That may be exactly what happened in this instance — a disinformation effort about disinformation efforts.

Whatever the motivation behind the website, the last-minute election surprise may serve as a teaching moment for Silicon Valley and US intelligence — both of which touted their preparedness for this year's election after acknowledging widespread failures in 2016. After all, even if these accounts had no real impact, they still managed to go undetected until just before the election.

Emails sent to the address on the website went unanswered Wednesday. A call to the lawyer representing Concord Management, a group allegedly associated with the IRA which is fighting Mueller's indictment in court in Virginia, was not returned.