Facebook said it has identified and removed hundreds of accounts and pages spreading misinformation on the platform ahead of the midterm elections — this time, with ties to Iran and Russia.

The company said it took down 652 pages, groups and accounts engaged to what it calls “inauthentic behavior” — misleading Facebook users about who they are and what they’re doing.

These coordinated misinformation campaigns sought to influence people across the globe, from the Middle East to Latin America to the U.K. and the U.S. It demonstrates how malicious actors continue to look to Facebook as a platform to spread political propaganda or sew discord.

Facebook CEO Mark Zuckerberg said the company was able to identify this damaging content because of its heavy investments in improving safety, security and privacy on the platform ahead of the midterm elections in the U.S. It’s also working to foster greater cooperation with law-enforcement and governments, to aid in the crackdown.

“Security is not something you ever solve,” he said during a call with the press. “You have to keep improving to stay ahead. The shift we made from reactive to proactive protection is a big change, and it’s going to make everyone safer.”

Last month, Facebook removed 32 pages and fake accounts seeking to inflame the U.S. electorate around divisive social issues — including one page targeting left-leaning activists, who had signed up to join a Washington, D.C., event to protest the Unite The Right 2 rally.

Nathaniel Gleicher, Facebook’s head of cybersecurity policy, said the latest round of removals was triggered by a tip last month from cybersecurity firm FireEye. It alerted Facebook to the Liberty Front Press, a network with ties to Iranian state-run media.

The first Liberty Front Press accounts were created as far back as 2013, with some attempting to conceal their location. These accounts spread political propaganda about the Middle East. Beginning in 2017, they turned their attention to the UK and US — posing as news and civil society organizations.

Some 155,000 Facebook users followed at least one of Liberty Front Press’ pages.

A second set of accounts Facebook removed had links to the Liberty Front Press and other accounts that had been disrupted in the past, Gleicher said. These accounts posed as news organizations, but engaged in cyberattacks, attempting to hack people’s accounts and spread malware.

About 15,000 Facebook users followed at least one of these pages.

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A third set of inauthentic accounts, the first of which was created in 2011, shared misinformation about Middle East politics in Arabic and Farsi, and also posted content about politics in the U.S. and U.K. in English. Facebook discovered these pages last August, and expanded its investigation as part of its stepped-up efforts head of the U.S. midterm elections.

These accounts had the broadest reach, attracting some 813,000 accounts following at least one of these pages.

“We’re still investigating, and we have shared what we know with the US and UK governments,” said Gleicher. “Since there are US sanctions involving Iran, we’ve also briefed the US Treasury and State Department.”

The final set of pages that were removed can be linked to sources previously identified by the U.S. government as having ties to Russian military intelligence services. Recent activity focused on politics in Syria and Ukraine — covertly spreading pro-Russian and pro-Assad content.

“Since 2016, we’ve made significant progress in stopping fake accounts,” said Facebook’s Guy Rosen. “We’ve discovered coordinated efforts, like these ones. We have new verification process. Our ad verification system flagged ads these groups attempted to run.”