||Airborne tactical networks (ATNs) have provided protected air-to-air communications for military aircraft for several decades. To support emerging and future warfighter needs, the next generation of systems will require significant improvements to provide higher capacity, longer range, greater flexibility, and increased interoperability. Governed by domain characteristics such as long transmission ranges, low-to-medium data rates, latency constraints, and link protection needs, the air tactical domain poses several unique requirements on link and network design. Developing next-generation ATNs requires an understanding of the airborne tactical domain, including the design constraints and challenges at various layers of the network stack. In this article, we provide an overview of the unique domain characteristics of ATNs and highlight the key design challenges and research areas associated with the physical, link, and network layers.