An amphibious assault ship is a type of amphibious warfare ship employed to land and support ground forces on enemy territory by an amphibious assault. The design evolved from aircraft carriers converted for use as helicopter carriers (and, as a result, are often mistaken for conventional fixed-wing aircraft carriers). Modern ships support amphibious landing craft, with most designs including a well deck. Coming full circle, some amphibious assault ships also support V/STOL fixed-wing aircraft, now having a secondary role as aircraft carriers.
The role of the amphibious assault ship is fundamentally different from that of a standard aircraft carrier: its aviation facilities have the primary role of hosting helicopters to support forces ashore rather than to support strike aircraft. However, some are capable of serving in the sea-control role, embarking aircraft like Harrier or the new F-35B variant of the Lightning II fighters for combat air patrol and helicopters for anti-submarine warfare or operating as a safe base for large numbers of STOVL fighters conducting air support for an expeditionary unit ashore. Most of these ships can also carry or support landing craft, such as air-cushioned landing craft (hovercraft) or LCUs.
The largest fleet of these types is operated by the United States Navy, including the Wasp class dating back to 1989 and the very similar America-class ships that entered service in 2014. Just as an aircraft carrier leads a carrier strike group in the US Navy, an amphibious assault ship leads an expeditionary strike group. Amphibious assault ships are also operated by the Royal Australian Navy, the Brazilian Navy, the Chinese People's Liberation Army Navy, the Egyptian Navy, the French Navy, the Italian Navy, the Republic of Korea Navy (South Korea) and the Spanish Navy.
The term amphibious assault ship is often used interchangeably with other ship classifications. It applies to all large-deck amphibious ships such as the landing platform helicopter (LPH), landing helicopter assault (LHA), and landing helicopter dock (LHD).
[Wikipedia]