A navy (sometimes called a maritime force) is the branch of a nation's armed forces principally designated for naval warfare and amphibious warfare; namely, lake- or ocean-borne combat operations and related functions. It includes anything conducted by surface ships, amphibious ships, submarines, and sea-borne aviation, as well as ancillary support, communications, training, and other fields; recent developments have included space related operations. This book discusses the issues facing the United States Navy, including warfare and counter-terrorism operations; leases on foreign-built ships; Navy force structure and shipbuilding plans; and aircraft carrier programs.