The Kremlin is turning to unwitting Americans and commercial public relations firms in Russia to spread disinformation about the U.S. presidential race, top intelligence officials said Monday, detailing the latest efforts by America’s adversaries to shape public opinion ahead of the 2024 election.

The warning comes after a tumultuous few weeks in U.S. politics that have forced Russia, Iran and China to revise some of the details of their propaganda playbook. What hasn’t changed, intelligence officials said, is the determination of these nations to seed the internet with false and incendiary claims about American democracy to undermine faith in the election.

“The American public should know that content that they read online — especially on social media — could be foreign propaganda, even if it appears to be coming from fellow Americans or originating in the United States,” said an official from the Office of the Director of National Intelligence who briefed reporters on condition of anonymity under rules set by the office of the director.

Russia continues to pose the greatest threat when it comes to election disinformation, authorities said, while there are indications that Iran is expanding its efforts and China is proceeding cautiously when it comes to 2024.