Facebook shut down two Russian disinformation networks operated by the nation's intelligence services and a third by people affiliated with a notorious troll farm that interfered in the 2016 U.S. presidential election, the company announced Thursday.

The networks focused their efforts in numerous nations in Europe and Asia, with relatively little reach among U.S. audiences, Facebook concluded. But the involvement of people and entities that previously had targeted American politics underscored the ongoing threat posed by Russia's disinformation machinery, which U.S. intelligence officials have said is also attempting to interfere in November's presidential vote.

"Today's disclosures are further evidence that Russia continues aggressive interference operations and broader influence operations aimed at divisions within countries and among allies," said Graham Brookie, director of the Atlantic Council's Digital Forensic Research Lab, which tracks disinformation and studied two of the three networks removed by Facebook.

The tactics described by Facebook and outside researchers who studied the same networks suggest Russia increasingly is using phony news sites and think tanks to lend credibility to its disinformation, in some cases involving unwitting freelance writers in the operations. This is a shift from the 2016 election and its immediate aftermath, when Russian operations used fake accounts on Facebook, Twitter, YouTube and other social media platforms to spread messages to mass audiences based on their political or demographic characteristics.

The shift has been driven by the growing need of disinformation operatives to avoid detection and removal by social media companies and U.S. government agencies, said Nathaniel Gleicher, head of cybersecurity policy for Facebook. One of the networks was discovered by Facebook after a tip from the FBI, which has been monitoring Russian and other foreign actors online.

"They've been forced into using less effective techniques, but they are still trying," Gleicher said.

The three Russian networks involved nearly 350 accounts, pages and groups on Facebook and its photo-sharing subsidiary Instagram. Overall the topics were wide-ranging and in line with Russian strategic themes, including the Syrian civil war, military conflict in Ukraine, Turkish politics, the coronavirus pandemic and the potential for civil unrest during the U.S. presidential election.

Rep. Adam Schiff, D-Calif., chairman of the House Intelligence Committee, issued a statement after Facebook's action: "This is just the latest reminder that the Kremlin is undeterred - and perhaps emboldened - in launching new online influence campaigns. We must continue to publicly expose all elements of Russia's foreign influence and propaganda machine so we can harden our defenses and improve our collective vigilance as we cast ballots and prepare to tally votes in November."

At least one of the networks, run by a phony think tank called the Strategic Culture Foundation, helped spread conspiracy theories aimed at English-speaking audiences, including by fueling false rumors that the coronavirus was produced as a bioweapon and that a potential vaccine would include tracking technology. The foundation, whose Facebook page was being followed by nearly 29,000 people, also spread false information that Bill Gates, the tech executive and philanthropist, was leading efforts to create a vaccine with surveillance capabilities.

"It seems that the elite are betting on the development of an ID-tracking vaccine that would bring all races and institutions under one roof, but clearly they will continue living in their own fenced-off neighborhoods in this one-world government," said a post from the foundation.

The foundation's website describes it as "a platform for exclusive analysis, research and policy comment on Eurasian and global affairs." The articles show a frequent focus on relations among the United States, Russia and other nations. One headline this week read, "The Propaganda Campaign Against Russia Is Gathering Momentum."

The State Department singled out the Strategic Culture Foundation in a report last month, concluding that it was "an online journal registered in Russia that is directed by Russia's Foreign Intelligence Service (SVR) and closely affiliated with the Russian Ministry of Foreign Affairs."

The foundation did not respond to a request for comment through its website, which is still operational.

Facebook acted against two networks run by Russian intelligence services, including one by the military's GRU intelligence agency that hacked and disseminated damaging Democratic Party emails in 2016, the company said. It did not specify the other intelligence agency, but the State Department report linked that network with Russia's civilian Foreign Intelligence Service.

A second report by the Atlantic Council's DRFLab detailed how people previously affiliated with the Internet Research Agency, the St. Petersburg-based troll farm that flooded social media with misleading posts that helped bolster support for President Trump during the 2016 election, are acting in stealthier ways this year.

"It's not clear that the Internet Research Agency still exists at the same scale and scope it did when exposed by independent Russian journalists or at the height of its activity targeting the United States before and after the 2016 elections," the report says.

Key to the recent Russian effort was a front group called "United World International" that posted content on Facebook and Instagram in English and Turkish, pushing anti-Western themes.

All of the networks removed by Facebook on Thursday worked to direct users to stand-alone websites run by Russian operatives that operate beyond the control of the social media company.

The content on focused on potential U.S. audiences had few followers and little apparent focus on the coming election, Facebook said.