At the same time, GAO said the Pentagon lacks a reliable estimate of what the full missile warning and tracking architecture will cost over its lifetime. As a result, GAO warned, SDA risks fielding satellites that do not meet operational needs. In that earlier assessment, GAO said SDA moved forward without proving that intersatellite laser communications — essential for moving missile tracking data quickly across the constellation — worked as intended. In the new report, GAO said SDA justified its technology readiness assessments by pointing to the availability of commercial products used in Tranche 1 and Tranche 2. List of recommendationsGAO also found problems in the ground segment, which is responsible for processing and distributing missile tracking data.