To provide insight into this question, first, DHS uses qualitative comparative risk assessments for strategic planning. It has various sets of homeland security risks such as terrorist events, major accident disasters and natural disasters. Homeland security risk is a challenging endeavor because of the nature of the risks with significant uncertainty. As a complex and large organization, DHS has multiple priorities which make it difficult for it to manage, prepare and respond to natural, terrorist and accident events. With the inherent challenges in terrorism and other challenges, risk assessment has been a challenging domain for DHS.
The Strategic National Risk Assessment in Support of PPD 8: A Comprehensive Risk-Based Approach toward a Secure and Resilient Nation, U.S. Department of Homeland Security, Editor, (2011) Washington, DC