In another possible sign of attempted foreign interference in the U.S. presidential election, Facebook Inc. revealed on Wednesday that it’s likely a Russian operation spent $100,000 on ads to promote certain views to targeted U.S. citizens.

According to a report in the Washington Post citing several unnamed sources,  the social media giant told congressional investigators that the ads promoted 470 fake accounts that promulgated polarizing opinions on such issues as political candidates, immigration, gun rights and LGBT rights.

Only a small number of the ads were focused on nominees Donald Trump and Hillary Clinton, although Facebook didn’t reveal which nominee was favored. The accounts have now been suspended.

In a blog post, Alex Stamos, chief security officer at Facebook, said the company had been investigating potential Russian interference in the U.S. election since news emerged about the possibility in recent months. It said it had discovered that the $100,000 had been used to buy roughly 3,000 ads connected to 470 accounts all “likely” associated with each other and operated out of Russia.

Facebook also said that about half of the money spent came from operations run out of the U.S., although it found that these accounts had the language set to Russian.

In April Facebook published a white paper detailing the spread of fake news on the platform and the ways the company was attempting to reduce it. The paper outlined some of the techniques used to propagate certain views to sway the public’s opinion or even sow the seeds of confusion.

“We have had to expand our security focus from traditional abusive behavior, such as account hacking, malware, spam and financial scams, to include more subtle and insidious forms of misuse, including attempts to manipulate civic discourse and deceive people,” Facebook said.

Adam B. Schiff, the senior Democrat on the House Intelligence Committee, said that Facebook’s revelation should be a “profound warning to us and others about future elections.”

However, he added that the investigation should continue to find out just how much of an impact such fake accounts had on the election. According to people familiar with the matter, Facebook still doesn’t know to what extent these accounts were coordinated.

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