One recent proposal is to build a new class of warship that includes the helicopter deck, well deck, amphibious vehicles, and Marines of a "gator" (amphibious assault ship) while also mounting the vertical-launch missile battery of a destroyer or frigate. The resulting ship could perform most of the missions now performed by the two different types of warships.
There are some obvious advantages. Building one class of warship instead of two or three would appeal to a Congress that is always complaining that the Pentagon is building too many different kinds of airplanes. A standardized class of battle-gators would simplify the training of crews and the maintenance of the ships. A relatively small crisis could be handled by a single ship which would carry the full range of options to apply force to a situation. This would have other advantages in that an adversary would not know which of these options would be used.
If budgets continue to force a reduction in the number of ships, battle-gators would mean that the Navy could keep the most real capability in the allowed smaller number of hulls. The large cargo volume would allow the ship to perform other roles, such as disaster relief and supporting the deployment of other forces such as an aviation unit. The ship could be easily and quickly reconfigured to perform a variety of missions.
On the other hand, there are some clear problems. Taking a typical Landing Ship Dock (already bigger than any destroyer) and adding a full destroyer load of missiles would require a bigger ship. Amphibious ships are much slower than surface warships, so the joint ship would need massive engines, and would grow bigger still. Carrying around a few hundred Marines would expose them to extra dangers if the ship was sent on a mission that did not require them. On a given mission, the ship might need to be at one location to support the troops and a different location to provide missile coverage to an area or to other ships. A ship that can do everything might not do anything as well as specialist vessels.--Stephen V Cole