Nonetheless, such a stretching is unavoidable. The new security problems are driven by powerful forces, reshaping the entire international context. They impose starkly different requirements. They will deflect even the impressive momentum of U.S. military traditions. The eventual outcome is uncertain. It turns upon political debates yet to be held, consensus judgements yet to form, and events and their implications yet to unfold. Fundamental reconceptualization of security policy is a necessary step in the right direction, and it is important to get on with it. Getting on with it means defining the new concept of cooperative security, identifying the trends that motivate it, outlining its implications for practical policy action, and acknowledging its constraints. These tasks are the purpose of this essay.