DNC raises concerns about Facebook's ability to catch trolls

The letter detailing concerns about Facebook's detection of nefarious campaigns on its platform comes just two months before the Iowa caucuses.

After Russia targeted the 2016 presidential election using Facebook, the company hired a team, which includes former intelligence officials, to root out misinformation campaigns and coordinated online troll groups.

Seema Nanda, the DNC's CEO, wrote in the November 21 letter that a small in-house team the DNC has monitoring online misinformation had uncovered and reported to Facebook "at least nine foreign, inauthentic account networks targeting Americans with anti-Democratic false news content."

The DNC said all of the campaigns appear to be commercially -- rather than politically -- motivated, but still "have the effect of warping the political perceptions of American voters and hurting Democratic candidates' electoral chances."

"It's concerning that we're able to uncover these terms-of-service-violating operations on a fairly regular basis, with a team far smaller than Facebook's. Considering Facebook's enormous financial resources and the stakes of the upcoming elections, we'd ask that you dedicate additional capacity to enforce your terms of service against these types of malicious actors," Nanda wrote.

Facebook had no immediate comment on the specifics of the letter Tuesday, but the company has previously confirmed to CNN that it has investigated and taken action on accounts as a result of tips from the DNC.

Earlier this year, Facebook and Twitter took part in a training session organized by the DNC for presidential campaign staff about how campaigns could share details of suspicious activity with the companies.

Facebook's team searching for what suspicious behavior on its platform has had a number of successes over the past year, including recently thwarting a network of accounts that appeared to be linked to the same Russian troll group that meddled in the 2016 US presidential election. The accounts appeared to be laying the groundwork for 2020.

The DNC led its letter to Sandberg with Facebook's controversial political ad policy. The company does not fact-check ads from politicians.

"Current Facebook policy allows politicians to place demonstrable lies in front of voters via paid ads. This type of elite disinformation, from politicians many voters trust, is one of the most insidious and damaging forms of disinformation. Facebook's advanced analytics and targeting capabilities, furthermore, allow candidates to direct disinformation at the populations most susceptible to it," Nanda wrote.

Nanda said Facebook should fact-check ads, but it should not go as far as banning political ads entirely -- a policy Twitter adopted amid increased scrutiny of how Silicon Valley handles political speech.

"Banning political ads or severely inhibiting targeting capabilities on Facebook would not be in our party's best interest nor in the best interest of promoting voter participation," she wrote.

Facebook CEO Mark Zuckerberg has defended the company's decision not to fact-check political ads.