The US Navy operates a number of Amphibious Expeditionary Force
that has dedicated missions which include 'force projection' into
hostile territories.
These Amphibious Expeditionary Force falls under the command of the
US Marines, which is a component of the US Navy.
There are quite a few combination of amphibious vessels to transort
the ships from home to the theatre of operation.
The Aircraft Carrier of vintage World War 2 design has largely been
used, the initial type being the Tawara Class with a rear entry to
a sheltered dock within the Carrier.
These types of vessels are terms as LHA, with the flight deck able
to accomodate several heavy helicopters landing and take off
simultaneously.
The Marines can be ferried to hostile territory by CH-52 or CH-42
Helicopters, or the future Osprey MV-22 VTOL Aircraft, or they can
embark in the sheltered dock onto Landing Craft Air Cushioned
(which are basically Heavy Lift Hover-Crafts).
An improvement to the LHA class Carriers were subsequently built,
and named the LHD; and a future type with new hull designs are
being planned - and presently designated as LHX.
View from within the dock, watching the entry of a Landing Craft
Utility.
The LSD are actually landing ship docks, similar to our Endurance
Class of Landing Ship Dock that replaced the WW2 LST (landing ship
tank).
The flight deck can only accomodate two heavy lift helicopter, and
leads into a hangar, while the dock area is entered from the rear
of the ship.
This design is to allow soldiers to board landing crafts utility or
landing craft air cushion in the safety of a sheltered dock
area.
Seen below is a future LPD-17 San Antonio designed for the
USN
Seen below is LPD-49 Harpers Ferry class,
Although ST Engineering has followed the LPD design, she prefer to
call the new Endurance Class an LST.
The LPD operated by the USN do not have the forward ramp-door
opening that allow "Roll-on and Roll-off" (RoRo) access, unlike the
LST Endurance class built by ST Engineering Marine for the
Singapore Navy.
The Singapore Navy Endurance Class LST carry its LCU as Life Boats
as well (see below).
For more information of the RSN Endurance LST, visit the following
web site of ST Engineering:
http://www.stengg.com/downloads/mari_140LST.pdf