Revelations about the Stuxnet computer worm raise the possibility of damaging cyberattacks on the US electrical power grid or other critical infrastructure. Several approaches might mitigate cyberthreats to critical infrastructure and information technology targets. Among them are efforts to defend the information systems that support important infrastructure, to deter enemies from cyberattacks on those systems, to reduce or eliminate the forces that might be used in cyberattacks, or to reach arms control agreements that limit or proscribe such cyberattacks. Although each of these approaches is unlikely to be successful in and of itself, each is worthy of further exploration. Taken together, they may yield benefits that make cyberspace more secure.