Neither campaign actively chose to have their ads run against Russia-backed or white supremacist content.

Instead, YouTube’s algorithms placed the campaigns’ political ads before videos from the Russian media outlet and white supremacist groups based on algorithms that automatically determine where such paid-for content should be shown, based on the demographics of YouTube views that individual advertisers want to target online.

The revelations come as advertisers question how they spend money on social media, with more than 400 companies, including Unilever, Coca-Cola and Ford, joining a boycott of Facebook because of the company’s handling of hate speech and misinformation. Google, which owns YouTube, has similarly faced a backlash after companies’ ads were shown alongside terrorist videos from ISIS.

“I was surprised to find this because of all of the attention around YouTube’s advertising,” Wendy Via, chief executive of the Global Project Against Hate and Extremism, told POLITICO. “Given all the attention focused on presidential campaigns, if they aren’t going to be protected from running ads against this type of content, how are other advertisers going to be treated?”

“This is unacceptable,” said Bill Russo, a Biden spokesperson, in a statement to POLITICO. “We will be demanding answers from Google on how our ads were played alongside this content and how we can be assured that it will never happen again.”

Representatives from the Trump campaign were not immediately available for comment.

After the report was published, Google said a technical error had allowed ads to run against the white supremacist channel, a glitch that has now been fixed. The company said the videos linked to Russian-backed media outlet had also now been limited from displaying ads because of violations of its content policies.

On Ruptly’s YouTube channel, Google runs a disclaimer that highlights the Russian government controls the media outlet.

But before a video titled “Austria: ‘We should send them back,’” a Trump ad asking people to rate the president’s actions, including a link to an online survey, was displayed, according to the Global Project Against Hate and Extremism. Similarly, a Biden paid-for message ran alongside a Ruptly video called “Italy: Generazione Identitaria hosts second ‘sports day in defense of homeland.'" Both videos have been viewed less than 4,500 times.

The same two campaign ads were also displayed before a white supremacist video linked to France’s “Generation Identitaire,” a domestic far-right movement started in 2012 that has called for the removal of non-white French citizens from the country. The YouTube video, from late 2013, has been watched almost 80,000 times.

Heidi Beirich, Global Project Against Hate and Extremism’s chief strategy officer, said several U.S and European security agencies, including the FBI, Department of Homeland Security and Europol, had flagged the white supremacist movement as potentially fomenting extremism and violence.

She added that YouTube must do more to flag such content and stop these channels from making money through online advertising.

“All these agencies say [the Identitarian movement] influences people to commit acts of terrorism,” she said. “There’s no reason YouTube is not acting.”