For just war doctrine to apply, the last resort requirement to exhaust all measures short-of-war must be fulfilled. Because of research and policy developments in the last fifteen years, the international community is now equipped with a richer understanding of how wars and atrocities evolve through time, improved precision about trigger points and risk factors that may accelerate that evolution, growing consensus on what prevention and mitigation steps to look for in that process, and new technologies for ascertaining these steps in order to intervene when mitigating action might deflect the escalation. It is thus argued that the responsibility of the international community to intervene in a timely and appropriate fashion has become increasingly clear and inescapable. It is further argued that the alert engagement of civil society in crafting this body of research and policy places a heavy public burden on government leaders to demonstrate that indeed all measures short-of-war have been exhausted. We now have at our collective disposal many more measures to deploy and many more witnesses to raise the alarm. Accordingly, the threshold for declaring that last resort has been reached has now become much higher.