As the deadly Russia-Ukraine conflict moves to new phases, the U.S., its allies, and partners must heed critical and emerging insights from this hot war. After more than one hundred days of high-intensity conflict, some clear and compelling initial insights for the U.S. and Allied Integrated Air and Missile Defense (IAMD) are emerging. The effectiveness of IAMD systems in countering both missiles and Unmanned Aerial Systems (UAS) have been critical elements in this conflict–with a continued evolution in competition between fires and the defender. A clear understanding of these dynamics and the key lessons they provide will be vital for the U.S. and its allies to mitigate capability and capacity shortfalls while enhancing and revising operational approaches in Europe, the Indo-Pacific, and elsewhere around the globe. These are initial insights and preliminary lessons learned, developed using open-source information, so additional insights and revisions are expected later, with the benefit of in-depth evaluation(s) and more complete data.