What does the term amphibious assault refer to?

Answer 1

In military terminology, an "amphibious assault" refers specifically to the movement of troops from a water-borne transport onto land. Historically, this has exclusively meant the use of small boats and similar craft to move troops and equipment from large vessels onto a beach (or, rarely, a prepared dock such as at a port), which may or may not be actively defended.

In modern times, it often includes some component of helicopter-borne troop movements. Thus, a modern amphibious assault generally consists of small units of troops being ferried ashore in special-purpose assault watercraft or hovercraft in combination with some troops being landed immediately behind the beaches by helicopters or parachute. The key portion of amphibious assault is the "over-the-beach" portion, where the vast majority of the fighting force comes ashore. If the attack primarily relies on other methods of transporting troops to the combat zone, then it is called some other form of "assault" (e.g. airborne assault, airmobile assault, etc.)