Russian trolls used Reddit to spread propaganda in prelude to the 2016 U.S. presidential election, Reddit said on Monday.
Reddit CEO Steve Huffman said in a post on Reddit that the company removed a “few hundred accounts” from its social media service that it believed were linked to Russian-based entities that had spread misleading information.
Huffman did not identify the groups, but the Daily Beast reported last week that members of the Russia-based Internet Research Agency had spread misinformation on Reddit’s various message boards as well as on Tumblr blogging service. The IRA was one of three Russian groups identified in a recent Justice Department indictment alleging that Russian individuals had spread fake news and propaganda through popular social networking and messaging services like Facebook (fb) and Twitter (twtr) in an effort to exacerbate existing divisions in the U.S..
“As for direct propaganda, that is, content from accounts we suspect are of Russian origin or content linking directly to known propaganda domains, we are doing our best to identify and remove it,” Huffman wrote. “The vast majority of suspicious accounts we have found in the past months were banned back in 2015–2016 through our enhanced efforts to prevent abuse of the site generally.”
“We don’t see a lot of ads from Russia, either before or after the 2016 election, and what we do see are mostly ads promoting spam and ICOs,” Huffman said.
Huffman also said that thousands of U.S.-based Reddit users may have unwittingly promoted Russian propaganda on the service. He cited the fact that these Reddit users endorsed the postings of @TEN_GOP Twitter account, which they thought were linked to a real Republican group but was actually a “Russian agent.”
Get Data Sheet, Fortune’s technology newsletter.
“I wish there was a solution as simple as banning all propaganda, but it’s not that easy. Between truth and fiction are a thousand shades of grey,” Huffman wrote. “It’s up to all of us—Redditors, citizens, journalists—to work through these issues.”
The Senate Intelligence Committee now wants more information from Reddit about the possibility that Russia may have exploited the service, the Washington Post reported Monday. The committee also plans to hold a briefing with Tumblr, the newspaper said citing an unnamed source.