For all their power, both the United States and China are increasingly vulnerable. Each faces a range of strategic dangers, from nuclear weapons to disruption of critical computer networks and space links.1 Because their relationship is at once interdependent and potentially adversarial, the United States and China are especially vulnerable to each other: interdependence exposes each to the other, while the potential for conflict impels each to improve strategic capabilities against which defenses can be futile. Strategic vulnerability cannot be eliminated, only mitigated.