One fundamental reason for maintaining a professional U.S. Army is the requirement to protect American citizens and their homeland. The United States’ geography has enabled it to avoid the recurring clashes between untrusting neighbors frequently seen in other parts of the world, but modern technology has shrunk the globe, making it more difficult by the day to guard the nation. The instability and uncertainty that define the global security environment today—including but not limited to complex terrorist networks, miniaturized weapons of mass destruction (WMD) and threats that emanate from even the most benign environments— now require the United States to prepare to respond to widely varying contingencies on its home soil.Implicit in the concept of strategic landpower— Army, Marines, special operations forces—is the ability to manage the consequences of a large-scale disaster or attack against the homeland. Such capability mitigates the direct effects of incidents and helps deter potential adversaries from harming Americans. In the immediate aftermath of a chemical, biological, radiological or nuclear (CBRN) event, a capable response would also inspire confidence in citizens that their government will prevail. However, the ensuing chaos can be overwhelming for even the most experienced and highly trained personnel. A successful response can be measured by the amount of time required for help to arrive, what forms of assistance are available, how much throughput the responders can provide and how well commanders can apply mission command in support of civilian authorities to create order out of chaos.According to Chairman of the Joint Chiefs of Staff General Martin Dempsey, six enduring national security interests are informing the ongoing 2014 Quadrennial Defense Review (QDR) analysis: survival of the nation; prevention of catastrophic attacks on the United States; protection of Americans abroad; security of the U.S. economy and global economic system; secure and reliable allies and partners; and the preservation and extension of universal values.2 In pursuit of the first two— prevention and survival of large-scale attack—the Department of Defense (DoD) coordinates a wide range of Title 10 (federal) and Title 32 (National Guard) forces with dedicated capability to provide prompt and sustained assistance at domestic incident sites. These forces have undergone significant evolution and augmentation over the past decade, but preparation for a CBRN incident requires constant vigilance and reassessment.U.S. Northern Command is the geographic combatant command responsible for defending the U.S. homeland. It exercises command and control over several service component commands—including U.S. Army North, which oversees and provides headquarters for DoD CBRN response assets. Among these, U.S. Army North has operational control of Joint Task Force Civil Support (JTF-CS), the nation’s only standing CBRN joint task force. To validate Title 10 CBRN response forces, U.S. Army North annually hosts joint exercise Vibrant Response, which simulates a joint emergency response to a CBRN incident in a major U.S. metropolitan area. U.S. Army North collaborates with the National Guard to help train and sustain the readiness of Title 32 CBRN response forces.