"Train like we fight, fight like we train" is an age-old axiom of military training. It is a training concept which is easy to grasp and makes sense. However, this training concept presupposes that we do, in fact, know how we are going to fight, in the last two years, the world has undergone significant political, social, and economic upheaval. The military community has had to evaluate the identity and nature of the threat, develop an appropriate set of countermeasures to the threat, and then temper the plan with the fiscal realities of shrinking defense budgets. All of this has meant a change in many mission requirements which must be reflected in the training of the military. This paper discusses the issues of providing sustainment training for aircrews in the face of rapidly changing mission requirements. It discusses the role of political, economic, and technological impacts upon the definition of the threat and of the mission. It then discusses the differences between mission rehearsal and sustainment training and suggests the concept of quick-response modification of existing training systems for sustainment training. Finally, it discusses an actual implementation of the quick-response modification to support rapidly changing sustainment training requirements for Army Aviators.