 The U.S. Missile Defense Agency, or MDA, and the Ground-Based Midcourse Defense Program Office, or GMD, conducted the GMD Weapon System Booster Vehicle Test 03, or GMBVT 03, demonstrating a unique capability of the GMD element of the missile defense system. This test was the first flight test of a three-stage booster operating in two-stage mode, meaning the third stage was not ignited, allowing earlier release of the kill vehicle, providing increased battle space. This new capability is known as 2-3-stage Selectable Ground-Based Interceptor, or GBI. This capability gives the warfighter greater flexibility in executing the defense of the homeland while significantly increasing the battle space for successful threat engagement. Using a mock-up of the exo-atmospheric kill vehicle, known as AMAS Modal Units, or MMU, provided a significant reduction in the cost of the test and spared critical defense assets that were not required in this non-intercept test. MDA assets participated from locations spanning thousands of miles from the broad ocean area in the Pacific Ocean to California and Colorado in the U.S. Land-based and mobile assets were positioned for the collection of test data from the GBI launch sites at Vandenberg Space Force Base in California and throughout its flight trajectory. The GMBVT 03 flight test began at Vandenberg Space Force Base with the launch of the GBI. After the first stage burnout, the second booster stage ignited and flew the MMU to its separation point. Following separation from the payload adapter, the MMU proceeded on a ballistic trajectory and disintegrated during reentry. Following separation of the MMU, the second and third stage booster assembly likewise disintegrated during reentry to the atmosphere, with minor debris splashing down and sinking into the Pacific Ocean. GMBVT 03 will support the fielding of the two-slash-three-stage Selectable Capable GBI. The new Selectable Stage Booster provides the warfighter with more engagement time and space, providing for greater defense and depth. Future upgrades to sensing and tracking capabilities when coupled with the Selectable Stage Booster will provide the warfighter with a robust ability to assess the threat after initial engagement while retaining the time to engage again if necessary. The ground-based mid-course defense system is a critical element of the nation's overarching missile defense system. In the face of an increasing enemy ballistic missile threat, the missile defense system is deployed to protect the nation, our deployed forces, and our friends and allies against enemy long-range ballistic missile threats.