This is the first announcement of this magnitude from Facebook about a coordinated influence campaign from Iran. Twitter followed soon after, saying it too had suspended 284 accounts "for engaging in coordinated manipulation." Those accounts too appeared to originate in Iran.
Facebook said it was tipped off by the cybersecurity firm FireEye, which said the network of accounts across social media platforms pushed "narratives [that] include anti-Saudi, anti-Israeli, and pro-Palestinian themes, as well as support for specific U.S. policies favorable to Iran," such as the U.S.-Iran nuclear deal.
"The activity we have uncovered is significant, and demonstrates that actors beyond Russia continue to engage in and experiment with online, social media-driven influence operations to shape political discourse," FireEye said in its initial report.