Millions of Americans are looking forward to the return of Sunday NFL football this weekend. And somewhere in St. Petersburg, a group of Russian trolls likely is too.

The same Kremlin-linked group that posed as Americans on social media during the 2016 US presidential election has repeatedly exploited the controversy surrounding the NFL and players who have protested police brutality and racial injustice during the National Anthem, playing both sides in an effort to exacerbate divides in American society.

The debate is almost certainly an irresistible one for the Russians, given that it includes issues of race, patriotism, and national identity — topics the Russian trolls sought to exploit during the run-up to the election, and have continued to focus on in the two years since.

CNN worked with researchers at Clemson University that have archived millions of tweets sent by the Internet Research Agency, a Russian troll group that was indicted by Special Counsel Robert Mueller in February. The accounts' links to Russia were discovered by Twitter, which provided details about them to Congress. The data shows the trolls repeatedly weighing in on the debate, using different accounts to take both sides. While they used some accounts to push petitions to fire the protesting players, they used others to hail them as heroes.

Over the past year, social media networks have identified and removed thousands of accounts tied to the IRA. But despite the tech companies' efforts, there's no indication that the group is shying away from the NFL controversy.

There is no question that the debate over the protests is real. But Americans watching the controversy unfold on social media ought to know that not all the outrage on either side is authentic, and not all of it is coming from US shores.

Clemson University researchers and CNN have found instances of accounts linked to Russian trolls by Twitter weighing in on the issue as recently as May of this year.

In March, an account posing as an African-American activist tweeted, "Just a reminder: Colin Kaepernick still doesn't have a job, because in this country fighting for justice will make you unemployable."

A group of suspected Russian-linked Facebook accounts posing as American activist groups that were removed from the platform in July had also referenced the controversy.

Darren Linvill, an associate professor at Clemson University who has been studying the Russian group's behavior with his colleague Patrick Warren, explained that the trolls "don't slant toward one side or the other in the NFL flag debate, but they do slant very steeply to both extremes," he said.

"Kaepernick is either a hero fighting a corrupt system or a villain who has betrayed his country. It's two very simple, divisive story lines told at the same time with the goal of dividing our country rather than adding nuance to an ongoing, important national conversation."