After the attacks of September 11, 2001 (9/11), the war against Afghanistan's Taliban "government," and the fall of Baghdad, the Secretary of Defense chartered a comprehensive review of the "transformational" defense strategy outlined in the 2001 Quadrennial Defense Review (QDR 01). The review resulted in the 2005 National Defense Strategy (NDS 05). QDR 01's defense strategy was, in a number of respects, overcome by strategic circumstances. Thus, NDS 05 was a necessary and timely adjustment to changes in the strategic environment's foundational conditions. NDS 05's development process gave birth to a novel description of the strategic environment-a view that is only imperfectly reflected in the Pentagon's now ubiquitous "quad chart" and its abridged description of the traditional, irregular, catastrophic, and disruptive challenges. The "quad" challenges and NDS 05's quite general description of the defense-specific response to them had a pronounced effect on the prevailing defense outlook and culture.