Two competing theories vie for dominance regarding the relationship between the U.S. military and the natural environment. On the one hand, because legal rules permit the military to disregard environmental laws when they conflict with the military’s national security mission, one might be left with the impression that the military always stands opposed to environmental protection. Yet the military is currently engaged in an extensive undertaking to improve its sustainable energy use by reducing demand and developing renewables in its multiple roles as a war fighter, a landlord, a first user of pre-commercial technologies, and a potential high-demand consumer. The military is undertaking such actions not only in response to congressional directives and presidential executive orders, but also voluntarily in response to its internal battlefield and national security needs. In some cases, the military is leveraging private financing rather than taxpayer funds to drive innovation. Such public-private partnerships among the military, private financiers, and technology firms are an essential form of collaboration with the potential to transform for the better not only our nation’s energy profile, but also the military-industrial complex. At the same time, however, these relationships warrant some caution to prevent rent-seeking. This collaboration represents a new Military-Environmental Complex.