Preserving health and medical care access during extreme demands on service delivery in a disaster or public health emergency is vital to the population and state, national and global security. Health security broadly encompasses the strategic, tactical, and operational infrastructure and hardening that ensures health system preparedness, the delivery of appropriate health and medical services, and swift recovery on behalf of impacted populations. This definition of heath security focuses on a measurable preparedness outcome by fostering resilience and meeting the critical and time-sensitive health and medical demands of affected communities. Health security as an inherent piece of quality health systems is a novel concept. Achieving health security in this manner requires a reengineered strategic approach. Responsibility and ownership for health security resides within the health care system. Like pieces of a puzzle, key health system components impacting disaster medicine and public health emergency readiness must be in place and include the following: planning, capacity & capability, public health preparedness, education & training, and scientific advancement. Utilization and integration of these components within the health system framework require excellence in the core tools of communication, collaboration and implementation. Health security, the often-missing piece of the health system, is now an inherent piece of the puzzle.