It remains to be seen in what context halting mass atrocities will next become a US military mission, but the challenge is virtually certain. Some argue that it is unlikely that, despite advocacy and education to the contrary, the United States will ever decide that it is within its national strategic interest to launch an intervention to stop a mass atrocity, and therefore that planning for this eventuality is not a priority. Such a position is not only ahistorical, it represents an abdication of responsibility to prepare for contingencies.

As a presidential hopeful, Barack Obama declared: “America deserves a leader who … responds forcefully to all genocides. I intend to be that President.” The recently issued US 2010 Quadrennial Defense Review states: “Not all contingencies will require the involvement of U.S. military forces, but the Defense Department must be prepared to provide the President with options across a wide range of contingencies, which include supporting a response to an attack or natural disaster at home, defeating aggression by adversary states, supporting and stabilizing fragile states facing serious internal threats, and preventing human suffering due to mass atrocities or large-scale natural disasters abroad.” (emphasis added)

This is essentially a warning order to the US military to be prepared to offer options to the national leadership in the event of the widespread killing of civilians.

Moreover, nations may not choose a MARO, a MARO may choose them. The next mass atrocity could emerge amidst an initially uncontested peacekeeping or humanitarian relief operation. The targeting of civilians, often an element of insurgency or civil war, could develop into a full-blown genocide or mass atrocity. Military actions to halt the targeting if civilians may therefore develop from, or even coexist with, other operational concepts in the context of a larger campaign in which US forces are engaged. For example, it is easy to imagine how systematic mass atrocities could emerge from a security vacuum created by the withdrawal of a foreign counterinsurgency force. Thus, mass killings could haunt US forces as they exit Iraq.