The ads that emerged, a sampling of the 3,000 that Russians bought during the 2016 presidential campaign and its aftermath, demonstrated in words and images a striking ability to mimic American political discourse at its most fractious. The targeting information also showed a shrewd understanding of how best to use Facebook to find and influence voters most likely to respond to the pitches.

As a group, the ads made visceral appeals to voters concerned about illegal immigration, the declining economic fortunes of coal miners, gun rights, African American political activism, the rising prominence of Muslims in some U.S. communities and many other issues. Some of the ads, many of which were bought in Russian rubles, also explicitly called for people to attend political rallies amid a campaign season that already was among the most polarizing in recent U.S. history.