We believe the "Day After..." exercise accomplished its goal. Stimulating discussions on the topic of R&D approaches to cyberspace security were held over five hours by some of the key governmental, university, and private industry resource persons who could contribute most to such a discussion. The exercise scenario seemed believable to participants; we heard no reactions that "Oh, that couldn't happen" (e.g., to the public switched telephone system, the energy system, the transportation system). The scenario focused the discussion on specific problems to be addressed, both with short-term expedients and longer-term R&D strategies.
Sixty participants were about the maximum that could be handled by the facilities and arrangements. If there are five groups of 12 discussants, it takes about an hour for all five groups to debrief and present their findings and observations to the plenary sessions. Two such plenaries, and at least three hours of group discussions (plus a working lunch, an introductory scene-setting session, and concluding remarks) totally absorbed the participants for five hours.
Would we do anything differently, based on this experience? The main lesson is one we have learned, and taken to heart, before: Vital information is gathered in serious walk-throughs and dry runs of the exercise; such activities cannot be shirked. For example, we believe it was crucial to the success of the exercise that the former three steps were cut down to two, and more time was allotted for the final step's discussion of current initiatives that might be undertaken. That insight came directly from the earlier dry runs we conducted.