Defense- and military-related R&D has shifted from component-centered hardware engineering toward software-defined, modular and continuously upgraded system architectures. This shift changes the nature of defense-to-civilian spillovers. We develop and probe a framework distinguishing between product spillovers, competence spillovers (know-how, system competence) and spin-in (civil-origin technologies integrated into defense systems). Using the SAAB Gripen fighter aircraft program (Gripen E) as a case, we combine survey data and interviews to assess the nature, magnitude and frequency of spillovers generated by the program. We find economically important competence spillovers (technology development benefits, quality-system tightening, production process improvements), while more traditional product spillovers are limited. The main conclusion is that programs based on modern digital systems-of-systems generate significant societal value primarily through spillovers of systems competence. These are economically significant but harder to observe and measure than traditional spillovers.