Joining Russia and other American adversaries, Iran has been behind a worldwide disinformation operation in the past several years, targeting hundreds of thousands of people, including in the United States, the Middle East, the United Kingdom and Latin America.

“As I’ve said before, security is not something that you ever fully solve,” Facebook CEO Mark Zuckerberg said on a call with reporters. “Our adversaries are sophisticated and well-funded, but the shift we have made from reactive to proactive detection is a big change and is going to make Facebook safer over time.”

The social-media giant said that Iran’s disinformation campaign has consisted of some now-removed accounts on Facebook and Instagram, which Facebook owns. These accounts purchased advertisements on Facebook to promote events.

Facebook traced the groups through various forensic ways, including “searching publicly available website registration information, and tracking IP addresses and Facebook pages sharing the same administrators,” according to The Washington Post.

The Islamic regime’s cyber mission has also included YouTube and Twitter, with the two companies deleting some of those accounts. Before Facebook’s announcement, the latter said it had removed 284 Iran-manufactured accounts, while the former had deleted at least one account created by the regime, according to its parent company Google.

Facebook said it has worked with law enforcement in the United States and Britain on the matter. It added it briefed both the Treasury Department and the State Department.

“I’ve been saying for months that there’s no way the problem of social-media manipulation is limited to a single troll farm in St. Petersburg, and that fact is now beyond a doubt,” said the top Democrat on the Senate Intelligence Committee, Virginia’s Sen. Mark Warner (D-Va.), according to the Post.

A third party, which Facebook did not identify, had been posting in Arabic and Farsi about Mideast politics. The content has been deemed anti-Israel, pro-Palestinian and anti-Saudi Arabia, in addition to supporting American policies favorable to Iran like the 2015 Iran nuclear accord, according to a blog post by FireEye, a company that provides services and products to prevent cyber threats.

The FireEye post stated it had identified Twitter accounts affiliated with Facebook pages that were linked to phone numbers with the +98 Iranian country code.

Additionally, FireEye observed “inauthentic social-media personas, masquerading as American liberals supportive of U.S. Senator Bernie Sanders, heavily promoting Quds [Jerusalem] Day, a holiday established by Iran in 1979 to express support for Palestinians and opposition to Israel.”