U.S. cybersecurity firm Mandiant, later purchased by FireEye, released a report in February 2013 that exposed one of China’s cyber espionage units, Unit 61398. The group, which FireEye called APT 1, is a unit within China’s People’s Liberation Army (PLA) that has been linked to a wide range of cyber operations targeting U.S. private sector entities for espionage purposes. The comprehensive report detailed evidence connecting APT 1 and the PLA, offered insight into APT 1’s operational malware and methodologies, and provided timelines of the espionage it conducted. FireEye termed Unit 61398 “APT 1” to indicate that the threat actor was an Advanced Persistent Threat, a type of operation in which the goal of the network intrusion is not only to gain access to a server or system, but also to retain ongoing access and engage in protracted cyber operations. The APT 1 report exposed the infrastructure of a cyber threat actor and gave both government and nongovernment organizations insight into the escalating nature of state-sponsored cyber operations.