A new internetworking architecture is needed to support tactical operations and survive close contact with a peer adversary while interconnecting heterogeneous subnetworks (RF, SATCOM, optical, etc.) where the limiting resource varies over time. This paper describes the results of a DARPA study that investigated what an Internet with these properties would look like if not constrained by the current Internet design. Five architectural components were identified which can work together to provide the necessary capabilities. Each is described and the research gaps required to develop it are identified. A set of new network-level behaviors, essential for future tactical operations, are described and mapped to the architecture. The paper is intended to initiate dialog with the networking community to help define potential future research in this area.