Navy and Marine Corps support national policies
Naval forces have been organized for fighting at sea or from the sea for more than two thousand years. The qualities that characterize most modern naval forces as political instruments in support of national policies are the same as those that define the essence of our naval Services today. These qualities are readiness, flexibility, self-sustainability, and mobility. They permit naval forces to be expeditionary (being able to establish and maintain a forward-based, stabilizing presence around the world). Naval expeditionary operations are offensive in nature, mounted by highly trained and well-equipped integrated task forces of the Navy and Marine Corps, organized to accomplish specific objectives. Naval expeditionary forces draw upon their readiness, flexibility, self-sustainability, and mobility to provide the National Command Authorities the tools they need to safeguard such vital national interests as the continued availability of oil from world producers and maintenance of political and economic stability around the globe. Through these qualities, naval forces reassure allies and friends, deter aggressors, and influence uncommitted and unstable regimes.
Three levels of war
The concept of "levels of war" can help us visualize the relative contribution of military objectives toward achieving overall national goals and offer us a way to place in perspective the causes and effects of our specific objectives, planning, and actions. There are three levels: tactical, operational, and strategic - each increasingly broader in scope. Although the levels do not have precise boundaries, in general we can say that the tactical level involves the details of individual engagements; the operational level concerns forces collectively in a theater; and the strategic level focuses on supporting national goals.
World War II, for example, a strategic-level and global war, included operational-level combat in the Pacific theater consisting primarily of U.S. led maritime, air, and supporting allied land campaigns. Within each specific campaign were a series of important and often decisive battles. At the tactical level, each contributed to the achievement of that campaign's objectives. The culmination of these campaign objectives resulted in overall victory in the Pacific theater.