Ukraine is the latest user of the American HIMARS (High Mobility Artillery Rocket System) vehicles that carry six GMLRS (GPS/INS guided MLRS). Ukraine knew of the success of the HIMARS vehicle and the capabilities of the GMLRS rockets. The latest version of the rocket can hit targets up to 85 kilometers away using INS/GPS (Inertial Navigation System/Global Positioning System) guidance. The INS component is important because it takes over if the GPS signal is lost due to jamming or when mountainous terrain blocks GPS as the rocket approaches the target. Over the last two decades INS has become more accurate. Russia has been a major source of GPS jammers since the 1990s. Two East Europe NATO members (Romania and Poland) use HIMARS. Several other NATO countries use HIMARS or the larger tracked MLRS vehicle (M270) that carries two pods. HIMARS is gradually replacing these. The HIMARS truck-mounted GMLRS system is ideal for Ukrainian artillery tactics, which makes use of individual self-propelled artillery to fire unguided shells at targets up to 40 kilometers away. This avoids return fire from the Russians, who are more vulnerable to Ukrainian tactics because Russia still employs mass artillery fire from batteries (six guns) or battalions (three batteries).
Each HIMARS system is carried in a 16-ton 6x6 U.S. Army truck with an armored (against small arms fire and shell fragments) crew cab. The vehicle carries one MLRS (Multiple Launch Rocket System) six rocket pod instead of two in the original larger, tracked, MLRS vehicle. Initially, a major attraction was that the 12-ton HIMARS truck could fit into a C-130 transport (unlike the 22-ton tracked MLRS) and was much cheaper to operate. The HIMARS vehicle can move at up to 85 kilometers an hour on paved roads and travel 480 kilometers on internal fuel. In 2016 it was revealed that HIMARS vehicles in American service had reached a million operational hours with a 99 percent readiness rate. The tech HIMARS used enables HIMARS to operate (move, receive a target order and launch the GMLRS) using as few as one of the normal three-man crew.
The first HIMARS entered service in 2005, about a year after GMLRS did. The two new innovations worked well together and were a major reason for the success of the GMLRS and the HIMARS rocket launcher. The U.S. no longer buys the tracked MLRS or unguided MLRS rockets. An MLRS pod with six GMLRS weighs 2.8 tons and has attracted a lot of export orders.
The 309 kg (680 pound) GMLRS missile is a GPS guided 227mm rocket. It was designed to have a range of 70 kilometers and the ability to land within meters of its intended target, at any range. This is possible because it uses GPS (plus a backup INS/inertial guidance system) to find the target location it was programmed with. With GPS the GMLRS will land within a few meters of the GPS coordinates. If the INS has to be used, that triples to about ten meters. In 2008 the army tested GMLRS at max range (about 85 kilometers) and found that it worked fine. This enables one HIMARS vehicle to provide support over a frontage of 170 kilometers. One HIMARS vehicle can provide precision fire support over an area of about 20,000 square kilometers. This is a huge footprint for a single weapon (an individual HIMARS vehicle), and fundamentally changes the way you deploy artillery in combat. By way of comparison, Excalibur (GPS guided 155mm shell) now has a max range of 55 kilometers.
GMLRS meant the MLRS fire control system was upgraded to handle precision targeting rather than just a general area. Since 2004 over 3,000 GMLRS rockets have been fired in combat with 98 percent accuracy (hitting the target) and over 50,000 have been produced. GMLRS rockets cost about $100,000 each initially and the current cost (a 2021 order) is $110,000 even after several upgrades. HIMARS meant even less work for tube artillery, which had dominated the battlefield since the 17th century. Export demand for HIMARS has meant the U.S. manufacturer has had to resume production for the growing number of foreign customers.
HIMARS uses a 28-ton Mk37 resupply vehicle to quickly rearm HIMARS vehicles that have used all their missiles. It carries two MLRS rocket pods and has handling equipment to remove an empty pod from a HIMARS vehicle and replace it with one containing rockets. The HIMARS battalions and ammo supply units use the MK37s to move loaded and empty MLRS pods into and out of the combat zone. The C-17, or similar military transports, can also fly in MK37 vehicles as well as additional MLRS pods with rockets and fly out the empty pods. Loaded MLRS pods are shipped four to a standard shipping container before resupply or firing (usually HIMARS) vehicles get them.
Early on most of the GMLRS rockets were fitted with an 89 kg (196 pound) M31A1 high explosive ("unitary") warhead. About half of that is actual explosives. That's twice as much explosive as the U.S. Air Force 130 kg (285 pound) SDB (Small Diameter Bomb). A 155mm artillery shell has 6.6 kg of explosives, and the 500-pound (227 kg) bomb has 127 kg of explosives, which produced an excessive blast for many urban combat situations. The GMLRS seemed to be just right most of the time.
The larger GPS guided ATACMS rocket (one per MLRS pod) has a range of 300 kilometers and a 230 kg (500 pound) warhead. This version has not been produced since 20o5 because other guided missiles with similar range and guidance systems made ATACMS less useful.
GMLRS has been used with great success in Iraq, Afghanistan and Syria where most have been fired so far. The guided rocket is much more effective than the older, unguided, version, and has replaced it for most users. The accuracy of GMLRS means that one rocket does the job that previously required a dozen or more of the unguided ones. That's why HIMARS is so popular. While HIMARS only carries six rockets, that's often enough to last for days in places like Afghanistan, even when there's a lot of combat. Ukraine expects to demonstrate that and a few new ideas as well. One reason NATO nations have been willing to deplete their own supplies of guided missiles and rockets is because the Ukrainians make the most of these weapons and have developed unique tactics against an opponent (Russia) armed with modern weapons.
Many users have developed unique uses for HIMARS and GMLRS. In 2017 the American marines found that with a few modifications to the HIMARS fire control software the vehicle could accurately fire GMLRS rockets from the flight deck of one of the many amphibious ships marines operate from. As far back as World War II the U.S. has 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 the next version of GMLRS, which enters service in 2022, has a range of 150 kilometers, making the ship-based version even more useful because it can support troops even farther inland. This GMLRS-ER also makes HIMARS more effective at supplying F-35s in stealth mode with more guided missiles. GMLRS-ER was originally called TC-GMLRS (Tail Controlled GMLRS) because it uses a new, tail-mounted guidance system to achieve high accuracy over longer distances. GMLRS-ER is the same size as the current GMLRS rocket and can be fired from existing pods after a software upgrade to the guidance system.
In 2018 the Marines found that the multitude of sensors on their new F-35B vertical take-off jets could spot ground targets in all weather and at night and pass the target location 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 is limited. HIMARS can supply 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. The air force could use this with their F-35As and the navy with their carrier-based F-35Cs.
HIMARS isn’t the first new missile system the marines found new uses for. In 2015 marines assigned to the new Yemen blockade force noted that many of the blockade ships were concerned about the Iran-backed Yemen rebels using small boat tactics to attack warships. The marines found that their FGM-147 Javelin ATGMs (Anti-tank guided Missiles) were a more portable solution that the TOW ATGM, which the marines called Saber. TOW/Saber were not as portable but had a superior fire-control system to finding and tracking and destroying small boats at night and in fog or mist. TOW has been around since the 1970s and remains in service because it is effective, inexpensive (compared to Javelin) and continually updated. This includes the fire-control system, which can also provide GPS coordinates for targets 4,000 meters distant and pass those coordinates on to aircraft, helicopters, armored vehicles or warships. The marine TOWs can be used from the deck of any size warship. The TOW tripod launcher and fire control system weigh 90 kg (200 pounds) and each missile about half that. This system can be delivered to destroyers or frigates via helicopter or small boat. The TOW has a longer range than Javelin (3,700 meters versus 2,500) and each TOW costs about $60,000 while a Javelin missile costs four times that. Javelin has the advantage of being lighter and easier to use, especially aboard smaller ships used for the blockade. The Ukrainians damaged at least one Russian assault boat using an unguided rocket. But there haven’t been enough target opportunities along the coast. The Ukrainians, like the American marines, have a tradition of improvisation.
Javelin has one of the best fire control systems for portable systems, but similar fire control systems are used in the marine LAV (light armored vehicles). These vehicles are similar to but preceded the army Stryker. The LAV has a 25mm autocannon which can also be used against small boats at ranges of up to 3,000 meters for a direct hit and twice that for area (less accurate) fire. LAVs are brought to the flight deck of navy amphibious ships. These ships carry dozens of vehicles below deck in a vehicle deck behind the hangar deck for aircraft. The vehicle deck opens to the rear of the carrier with a dock where landing craft take the vehicles to shore while the flight deck is used for helicopters and F-35B jets that can take off and land like a helicopter. The elevators that bring aircraft to the flight deck can do the same with vehicles.