An early classified Defense Department cybersecurity exercise named “Eligible Receiver 97” (ER97) featured a previously unpublicized series of mock terror attacks, hostage seizures, and special operations raids that went well beyond pure cyber activities in order to demonstrate the potential scope of threats to U.S. national security posed by attacks in the cyber domain, according to recently declassified documents and a National Security Agency (NSA) video posted today by the nongovernmental National Security Archive at The George Washington University.

“Joint Exercise Eligible Receiver 97”, run during the Clinton presidency, is frequently pointed to as a critical event in the United States’ appreciation of threats in cyber space. The exercise led directly to the formation of what would eventually become United States Cyber Command (USCYBERCOM) and informed key studies such as the formative Marsh Report on critical infrastructure protection. Despite the significance of ER97, however, very little is publicly known about the exercise itself.

ER97 involved an NSA Red Team playing the role of North Korean, Iranian and Cuban hostile forces whose putative aim was to attack critical infrastructure as well as military command-and-control capabilities to pressure the U.S. government into changing its policies toward those states. An interagency Blue Team was required to provide recommendations to personnel enacting defensive responses. Until now, only two phases out of three (infrastructure and command-and-control) had been publicly known.  The video and documents posted today provide new details about the third phase involving kinetic attacks in the physical domain – i.e. more traditional terrorist assaults on civilian targets – which were built upon intelligence gathered through the Red Team’s successes.