Widespread civil violence inside the United States would force the defense establishment to reorient priorities in extremis to defend basic domestic order and human security. Deliberate employment of weapons of mass destruction or other catastrophic capabilities, unforeseen economic collapse, loss of functioning political and legal order, purposeful domestic resistance or insurgency, pervasive public health emergencies, and catastrophic natural and human disasters are all paths to disruptive domestic shock. An American government and defense establishment lulled into complacency by a long-secure domestic order would be forced to rapidly divest some or most external security commitments in order to address rapidly expanding human insecurity at home. Already predisposed to defer to the primacy of civilian authorities in instances of domestic security and divest all but the most extreme demands in areas like civil support and consequence management, DoD might be forced by circumstances to put its broad resources at the disposal of civil authorities to contain and reverse violent threats to domestic tranquility. Under the most extreme circumstances, this might include use of military force against hostile groups inside the United States. Further, DoD would be, by necessity, an essential enabling hub for the continuity of political authority in a multi-state or nationwide civil conflict or disturbance.