Meta says it recently removed a network of thousands of fake and misleading accounts based in China.
The users posed as Americans and sought to spread polarising content about US politics and US-China relations.
Among the topics the network posted about were abortion, culture war issues and aid to Ukraine.
Meta did not link the profiles to Beijing officials, but it has seen an increase in such networks based in China ahead of the 2024 US elections.
China is now the third-biggest geographical source of such networks, the company said, behind Russia and Iran.
The recent takedowns were outlined in a quarterly threat report released on Thursday by the parent company of Facebook, Instagram and WhatsApp.
The China-based network included more than 4,700 accounts and used profile pictures and names copied from other users around the world.
The accounts shared and liked each other's posts, and some of the content appeared to be taken directly from X, formerly Twitter.
In some cases the accounts copied and pasted verbatim posts from US politicians - both Republicans and Democrats - including former House Speaker Nancy Pelosi, Michigan Governor Gretchen Whitmer, Florida Governor Ron DeSantis, Reps Matt Gaetz and Jim Jordan, and others.
The network displayed no ideological consistency.
In examples released by Meta, an account in the China-based network reposted the words contained in a tweet earlier this year by Democrat Congresswoman Sylvia Garcia. She criticised Texas's abortion laws and wrote: "Let's remember - abortion is healthcare."
But another account in the network copied-and-pasted a tweet from Republican Representative Ronny Jackson, who wrote: "Taxpayer dollars should NEVER fund travel for abortions."
Meta's report stated: "It's unclear whether this approach was designed to amplify partisan tensions, build audiences among these politicians' supporters, or to make fake accounts sharing authentic content appear more genuine."
The company's moderation rules forbid what Meta calls "co-ordinated inauthentic behaviour" - posts by groups of accounts that work together and use false identities to mislead other users.
Often the content shared by such networks is not false and references accurate news stories from major media outlets. But instead of being used for legitimate comment or debate, the posts are meant to manipulate public opinion, push division and make particular viewpoints seem more popular than they really are.
Meta said the large Chinese network was stopped before it took off among real users.
Ben Nimmo, who leads investigations into inauthentic behaviour on the company's platforms, said such networks "still struggle to build audiences, but they're a warning".
"Foreign threat actors are attempting to reach people across the internet ahead of next year's elections, and we need to remain alert."
The company said it also discovered two smaller networks, one based in China and focusing on India and Tibet, and one based in Russia which posted primarily in English about the invasion of Ukraine and promoted Telegram channels.
Russian networks, which prompted the company to focus on inauthentic campaigns following the 2016 election, have increasingly focused on the war in Ukraine and have attempted to undermine international support for Kyiv, the report said.
Meta also noted that the US government stopped sharing information about foreign influence networks with the company in July, after a federal ruling as part of a legal case over the First Amendment that is now under consideration by the Supreme Court.
The case is part of a larger debate about over whether the US government works with tech companies to unduly restrict the free speech of social media users.
Source: BBC