Although many authors have written about invation in general, only three have developed models that focus on military invation. Each one centers his model on what he considers the most significant dynamic of military invation. One author claims that military invation results from energetic civilian intervention into hidebound military organizations, ather rejects this claim and argues that internal dynamics cause military services to invate, while ather claims that interservice rivalry and competition stimulates invation. The problem with these models is t with their individual explanations, but that the practitioner often finds components of each of the models in the real world. This makes analyzing past invations difficult, but poses a real dilemma for the decision maker who wants to stimulate invation.