During the hybrid armed conflict in which Russia became involved — the Special Military Operation — the medical service of the Armed Forces faced a number of challenges. This review analyzes foreign publications indexed in PubMed® concerning the conditions and factors affecting the activities of the medical services of armed forces, primarily those of NATO countries. It was revealed that a limiting factor for operational effectiveness is the staffing levels and qualitative composition of medical personnel, their preparedness to provide care for the specific pathologies of wartime, and maintaining these competencies in an up-to-date state. Important conditions for successful provision of medical care are preserving the integrity of medical facilities during targeted attacks on them, and the ability to use infrastructure in hostile or newly occupied territories. Prehospital care serves as a limiting factor in reducing lethality, with the main causes being fatal hemorrhages and head injuries from mine-blast trauma. Proper tourniquet application, rapid evacuation, and blood transfusions make the greatest contribution to reducing prehospital mortality. Among casualties, those with limb wounds are most significant, as they subsequently create the greatest social burden on the state, exceeding the “years lived with disability” parameter for all other disease classes, including oncological and cardiovascular diseases. In modern conflicts, the most dangerous in terms of lethality are mine-blast injuries (61.4–83.5%) and head injuries (20.9–59.0%), and in terms of subsequent disease burden, limb injuries (45.7%) constitute an absolute majority and are the point of focus for the main efforts of the medical services of the warring states’ armed forces. At the same time, there are no unified approaches regarding the place of application of qualified and specialized care among countries.