The U.S. Navy has discovered that new sensors/fire control systems on marine combat vehicles carried on amphibious ships can provide an LHA or LHD amphibious ship with additional capabilities to detect and destroy small boats some nations (Iran, North Korea, China) maintain and train to “swarm” larger warships. The marine LAV 25 8x8 wheeled armored vehicles are equipped with a new fire control system called Saber. This is basically the ITAS-FTL (Target Acquisition Systems and Far Target Location) that the army has already adopted. This system includes GPS, an optical sight with FLIR (forward-looking infrared) and a laser range finder (range of 10 kilometers). Thus LAV 25s armed with TOW anti-tank missiles or 25mm autocannon gunner always knows where he is and can use that information if they receive warnings of hostile small boats or helicopters in the area from other ships or aircraft.
The marines found that Saber was much better at spotting small boats at sea, especially at night or in bad weather, than the usual sensors (air and sea search radars and lookouts) the ships used. The navy has eight Wasp class LHDs and each carries a MEU (Marine expeditionary unit) containing 2,200 marines and up to 16 LAV 25s. A couple of these can be brought up from the vehicle deck to the flight deck, parked near the edge of the flight deck (secured with cables in case the seas are rough) and stand watch when passing through waters where hostile small boat swarms may be encountered. Until now these swarms could interfere with the movement of larger ships (which the Chinese do often in the South China Sea) or pose an attack threat (as the Iranians do in the Persian Gulf) and it is known that these swarms (a dozen or more small boats armed with heavy machine-guns, anti-tank missiles or packed with explosives for a suicide attack) can, under right visibility and weather conditions, get close enough to larger ships to make an attack. The Saber sensors can track small moving boats at sea and instantly provide the 25mm autocannon or TOW missile gunner with accurate target information. This enables the 25mm autocannon to his these boats at up to 3,000 meters or the TOW at up to 3,700 meters. The 25mm autocannon can deliver less accurate warning shots at up to 6,000 meters. A MEU also has with it two or more M1 tanks with a fire control system that has more than twice the range of Saber and a 120mm gun with range to match. It is unknown if the navy has yet experimented with bringing an M1 or two onto the flight deck to assist in ship defense.
The marines have already tested the use of M142 HIMARs (High Mobility Artillery Rocket System) guided rocket vehicles on the flight deck of an amphibious ship. In 2017 the marines found that with a few modifications to the HIAMRS fire control software the vehicle could accurately fire GMLRS (GPS guided MLRS) rockets from the flight deck of one of an LHA or LHD ships. This is actually nothing new as during World War II U.S. forces fired unguided rockets from ships in support of amphibious operations. But the use of GMLRS meant HIMARS could provide precision fire support from a ship at sea and hit targets up to 85 kilometers away. The next version of GMLRS will have a range of 135 kilometers, making the ship-based version even more useful because it can support troops even farther inland. The new GMLRS has already been successfully tested at ranges up to 110 kilometers. This TC-GMLRS (Tail Controlled Guided Multiple Launch Rocket System) rocket is the same size as the current GMLRS rocket.
The U.S. Marine Corps has also found new ways to use their HIMARS vehicles firing GMLRS rockets in cooperation with the six F-35B vertical takeoff warplanes each LHA or LHD carries. In 2018 the Marines found that the multitude of sensors on their new F-35Bs could spot ground targets in all weather and at night and pass the target location on to a nearby HIMARS vehicle that would then fire a GMLRS rocket at the target. To maintain maximum stealth capabilities the F-35 carries bombs and missiles internally but the capacity of the internal bomb bays are limited. HIMARS can supply the guided weapons for one or more F-35Bs. Some helicopters are equipped with similar sensors and digital communications systems and can also pass on GPS target data to a HIMARS vehicle. An F-35B could even maintain its stealth by sending the target information via an encrypted burst transmission that is difficult to use for location finding. No reason why the GMLRS rockets could not be fired from the deck of an LHD.
The army has also found the new fire control systems available to several ATGMs (anti-tank guided missiles) had dual use as just a more powerful sensor, particularly at night and bad weather. The marines saw that this would work from the deck of an LHD as well and it did.