The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest, most capable navy in the world, with the highest combined battle fleet tonnage. The U.S. Navy has the world's largest aircraft carrier fleet, with eleven in service, two in the reserve fleet, and two new carriers under construction. The service has 322,421 personnel on active duty and 107,577 in the Navy Reserve. It has 276 deployable combat vessels and more than 3,700 operational aircraft as of June 2017[update].
The U.S. Navy traces its origins to the Continental Navy, which was established during the American Revolutionary War and was effectively disbanded as a separate entity shortly thereafter. It played a major role in the American Civil War by blockading the Confederacy and seizing control of its rivers. It played the central role in the World War II defeat of Imperial Japan. The 21st century U.S. Navy maintains a sizable global presence, deploying in strength in such areas as the Western Pacific, the Mediterranean, and the Indian Ocean. It is a blue-water navy with the ability to project force onto the littoral regions of the world, engage in forward areas during peacetime, and rapidly respond to regional crises, making it a frequent actor in U.S. foreign and military policy.