The development of open source software is currently arousing increasing interest in the IT world. This research inquires some specific paths enlarging the traditional view over open source software in inquiring the US Department of Defense (DoD) and the dynamics associated its front- and back-office activities. We explain how distinguishing basic administration from operational constraints and weapon R&D dynamics introduces specific governance concerns among public and private stakeholders. By no longer defining open source solutions as mere goods, but as services characterized by a flow of knowledge, we particularly highlight new emerging strategies of technological acquisition. Our analysis leads to revise the traditional role focusing mainly on cost issues and introduces open source software with distinctive properties serving the management of innovation and technological agility at the level of complex systems, exemplified here with the constraints associated to weapon systems and the Network centric warfare doctrine.