On Thursday, Facebook announced that it had suspended around 200 accounts run by some attackers in Iran belonging to a cyber espionage operation.

The operation targeted mostly U.S. military personnel and people working at defense and aerospace companies.

The group, dubbed “Tortoiseshell” by security experts, used fake online personas to build trust with targets and drive them to malicious websites that would infect their devices.

Facebook said the group would use messaging, email and collaboration services to spread malware.

Hackers mainly targeted people in the U.S. and U.K.

Facebook has blocked the malicious domains and Google said it has added related domains to its “blocklist.”

For more information, read the original story in Reuters.