Facebook has previously officially noted that 470 accounts associated with Russia's Internet Research Agency have been banned related to the 2016 election, plus 270 more in Russia just last week. But in today's testimony Mark Zuckerberg also mentioned a much higher estimate of "tens of thousands," though the confidence in this number would be also be much lower.
"In the IRA specifically, the ones we've pegged back to the IRA, we can identify 470 in the American elections, and the 270 that we went after in Russia last week," he began in response to Senator Feinstein (D-), who had asked about the numbers of accounts associated with this type of coordinated disinformation campaign.
But then he continued:
"There are many others that our systems catch which are more difficult to attribute specifically to Russian intelligence, but the number would be in the tens of thousands of fake accounts..."
The tens of thousands number must be taken with a grain of salt, since clearly Facebook has not been able to definitively attribute more than the stated 740 or so to the IRA and Russian intel. But it is still significant; this is clearly different from the 30,000-odd accounts banned in relation to France's election. That was a specific number and also not mentioned in connection with Russia specifically, as this estimate was.
It seems clear that Facebook is being conservative in its enumeration of Russian-linked accounts, and that very well may be the responsible thing to do. But Zuckerberg's remarks today establish a ceiling in the tens of thousands in addition to the floor of several hundred. That's worth keeping in mind.