Recent advances in computational fluid dynamics (CFD) algorithm development and high performance computing have contributed extensively to the transition of CFD into the design and testing environment of defense acquisition programs. During the past seven years, the U.S. Army’s Theater High Altitude Area Defense (THAAD) program has aggressively pursued major computational efforts addressing basic missile aerodynamics and lateral jet interaction (JI) effects associated with the divert and attitude control system. More recently, tremendously complex analysis results have been obtained very efficiently using high priority computing resources under a DOD Challenge Project granted by the High Performance Computing Modernization Office (HPCMO). THAAD has been participating in the Challenge program for the past three years to solve detailed aerodynamic design problems with high fidelity engineering analyses. This paper discusses the success that has been achieved in the design and testing of the THAAD interceptor through extensive utilization of CFD for the most stressing aerodynamic problems and for closer scrutiny of flight anomalies prior to two successful intercepts. Closed book comparisons between CFD analyses and ground test data are presented for single divert jets, multiple attitude control jets, and divert and attitude control jet combinations. Discussions of scaling from ground test to flight conditions and some comparisons with THAAD flight data will be highlighted. We demonstrate how a much better understanding of JI control effects has been achieved through timely analyses, and in turn how this significant increase in engineering capability strongly advocates the view that HPCMO effectively supports the warfighter.