As Roman military science essayist Flavius Vegetius Renatus said ca. AD 378, qui desiderat pacem, praeparet bellum : whoever desires peace should prepare for war.
The U.S. Navy was established and primarily exists to win the nation’s wars at sea. Together with other services, it also contributes to maintaining peace and deterring war. The Navy conducts diverse operations short of war ranging from support of foreign policy and military/theater strategy, combating transnational terrorism and piracy, providing humanitarian assistance/disaster relief, and freedom of navigation and overflight to support of insurgencies and counterinsurgencies. But the primary focus should be on preparing to fight a strong potential opponent(s) at sea. Obviously, a navy that is capable of defeating an enemy in a high-intensity conventional confrontation could, with the proper doctrine and training, successfully accomplish diverse tasks in peacetime and operations short of war. But the opposite is not true.