PrSM
The US Army Precision Strike Missile (PrSM) has been in competitive development since 2016 as a next generation longer range missile that can be fired from currently field MLRS and HIMARS.

Published in the February/March 2021 Issue – Enhancing the delivery of long range precision fires (LRPF) is being driven largely as a potential response to the increasing presence of A2/AD (anti-access area denial) defences on the battlefield.

According to international security scholars Stephen Biddle and Ivan Oelrich, A2/AD uses “a series of interrelated missile, sensor, guidance, and other technologies designed to deny freedom of movement” to an opponent’s air, naval and ground forces. It is the restrictions that in-depth air defence networks place on friendly attack aircraft contributing to the battle that are a primary concern to militaries like the United States, NATO, and those with a considerable air arm.

An effective A2/AD can prevent aircraft from striking and neutralising enemy forward and supporting forces, an advantage that US and western forces have relied upon for over five decades. LRPF uses ground based indirect fire systems to disrupt and destroy key elements of A2/AD. The objective is to break the interlocking defence network allowing attack air to operate with lower risk. As Brigadier General John Rafferty, who leads the US Army Long Range Precision Fires Cross-Functional Team, has made clear: “The combination of long-range air defence systems, artillery and coastal defences with seamless integration of long-range, over-the-horizon radars will be difficult to counter.”

Extending the Range

Current tube artillery and even ground missiles have limited capability to attack many of the critical elements that constitute the A2/AD system. Tube artilleries have a maximum range of 30-40km (18-25 miles). The BAE Systems towed 155mm M777 howitzer can deliver high explosive rounds to 28-37km (17-23 miles). With its Excalibur GPS guided round this increases to 40km (25 miles) while also providing a five metre circular error probable (CEP) accuracy. Likewise, the Lockheed Martin Multiple Launch Rocket System (MLRS) and its truck mounted cousin HIMARS was originally fielded to counter massed armour and counter-battery targets using M26 rockets with submunitions at up to 32km (20 miles). With air defence missile systems such as the Russian NPO Almaz S-300 (SA-10 Grumble) and S400 (SA-21 Growler) reaching out to 250-400km (155-250 miles) and even mobile systems like the GSKB Almaz-Antey. S350 having a 120km (74 mile) range, these indirect fire systems cannot hope to address them. Gen. Rafferty, who leads the US Army Long Range Precision Fires Cross-Functional Team explained: “With adversaries investing so heavily in countering air power it really has to be surface-to-surface fires that begin to reduce the enemy integrated air defences and long-range artillery that make up that layered standoff of A2/AD.” However, to engage and disrupt these systems requires achieving much greater range while retaining accuracy. This goal is the objective behind several development efforts.

artillery-projectile-
The application of the ramjet concept to artillery projectile offers a doubling or tripling of the range of existing howitzers without need to change their configuration.

Extended Range Artillery

Gaining a substantial increase in the distance that a cannon can fire a projectile is the focus of several projects. The US Army XM1299 long-range precision fires prototype (known as Increment IC) in its ERCA (Extended Range Cannon Artillery) programme was demonstrated in March 2019 in order to achieve the required accuracy at ranges up to 62km (38 miles). This was achieved by using a longer barrel combined with a new super-charged XM654 propellant that creates a much higher velocity together with XM1113 rocket assisted and XM659 projectiles.

In its accelerated programme, in 2019 the US Army awarded a $45 million contract to BAE Systems to integrate the new cannon into a M109A7 Paladin chassis. This reflects its intention to field 18 ERCA equipped self-propelled guns in 2023. Automatic loading is to be added later. According to a US Government Accountability Office (GAO) study “the middle-tier acquisition rapid prototyping effort for the XM1299 long-range precision fires prototype known as Increment IC – which includes new armament, electrical systems, and other upgrades – will cost approximately $486 million.” This would provide the Army one battalion of 18 howitzer prototypes for operational test.

ERCA
The US Army developed Extended Range Cannon Artillery (ERCA) has demonstrated its ability to deliver the Excalibur guided projectile to a range of 62 km.

Russia’s debut of its 2S35 Koalitsiya-SV 152mm self propelled howitzer occurred in 2015 with reports now indicating it is beginning to enter wider service. With a claimed maximum range of 70km (43 miles) and fully automated loading and firing at a sustained rate of 15 rounds/minute (rpm), its performance is comparable to the German Krauss-Maffei Wegmann (KMW) / Rheinmetall PzH2000 155mm 52 calibre system while exceeding that of most currently fielded artillery. The PzH2000 is also automated and demonstrated a firing range of 67km (41 miles) in November 2019 tests in South Africa. First introduced in 1998 the system is used by eight armies.

Concurrently, a technology referred to as ramjet has been demonstrated that will extend the range of a gun. The ramjet uses the projectile’s forward motion to compress incoming air which, expelled from its base, accelerate its flight. A key advantage of the ramjet is that it can reach extended ranges using 52 calibre guns already in wide use. According to Thomas Danbolt, vice president large calibre ammunition at Norway’s NAMMO, “the company in 2018 demonstrated its 155mm-ER ramjet ammunition capable of 40km (25 mile) range.   It is now combining the ramjet with rocket assist to extend this range to 70-85 km (43-50 miles) with a further goal of achieving 100-150km (62-93 miles) in future evolution”. NAMMO is working with Boeing, while General Dynamics Ordnance and Tactical Systems, Northrop Grumman, and Raytheon Missiles and Defense all have similar Phase One contracts to develop the XM115 ramjet round for the US Army with the aim of reaching targets at 100km (62 miles).

The US Army is also working on a new, long-range cannon it proposes to reach out and strike targets at up to 1,850km (1,150 miles). In comparison, US Navy battleships 16-inch Mark 7 guns could only hit targets at a maximum of 32km (20 miles) range. The Strategic Long-Range Cannon (SLRC) based on an Army Research Lab (ARL) briefing shows a concept reminiscent of the Cold War Army’s M65 ‘Atomic’ 280mm cannon and the modified 16-inch naval gun employed in the US-Canadian High Altitude Research Project, or HARP. Presently, the National Academy of Science is conducting a congressionally mandated study to assess the technology approaches, policies, and concepts of operations of the SLRC including the essential technologies, materials, and manufacturing capabilities needed. The committee has met in closed session four times, most recently in early December 2020. As Dr. Loren Thompson at The Lexington Institute points out: “Reflecting that the distance from Warsaw to Moscow is only 1,126km (700 miles) , the SLRC projected capabilities raises a number of questions including how they would be employed, how targeting would be performed, and who would control them.” These may be of as much or greater relevance than the technical challenges themselves.

Missiles

MLRS M260 and HIMARS have filled the general support role for many armies. Adapting it to delivery long range precision fires began with the introduction of the M31 GMLRS Unitary rocket. With its GPS guidance and a single 91kg (200lb) high-explosive warhead, the M31 could hit targets accurately while reducing with collateral damage. GMLRS has a minimum range of 15km (nine miles) but maximum of 70km (43 miles) with a velocity of Mach 2.5. Its upgraded multi-mode fuse includes point detonation, delay and a proximity airburst mode that can be set for three or 10 metres (9.8 feet or 32.8ft) Height Of Burst (HOB). These expand its utility against a wider range of deep targets.

For deeper targets out to 300km (186 miles) Lockheed Martin has developed ATacMS. Originally also a submunition carrier the latest MGM-168 Block IVA variant substitutes a 230kg (500lbs) unitary HE warhead with GPS/INS guidance. Fielded in 2002 it is fired from the MLRS or HIMARS – two missiles are available on the former but only one on the latter. However, the Army is seeking to introduce a successor to ATacMS as early as 2023. Named the Precision Strike Missile (PrSM), the programme was initiated as a competition in 2017 but is now solely being developed by Lockheed Martin (LMCO). It was to initially have a range of 60-499km (37-310 miles) (meeting the INF treaty limits). This may no longer be the case as a 2020 LMCO briefing added “it’s open architecture to ensure capability can easily be spiralled to achieve longer ranges.” The PrSM program, as Gen. Rafferty explained during his briefing “seeks to attack a variety of targets…We want the range [of PrSM] but then we also want to explore targets across multiple domains. We believe the multimode seeker will give us the ability to do.” This would see by 2025 an extended range ground launched capability able to not only address stationary land targets but potentially ships underway at sea.

PrSM
The US Army Precision Strike Missile (PrSM) has been in competitive development since 2016 as a next generation longer range missile that can be fired from currently field MLRS and HIMARS.

The guided missile has been the primary tool for use at the strategic level since the 1950s (largely following the German V1 and V2 rockets of World War II). The US Army fielded the Pershing missile through 1991 with a 1770km (1,099 mile) range with either conventional or nuclear warhead. It also in 1983 fielded the BGM-109 Ground Launched Cruise Missile (GLCM) a mobile land-based version of the Naval Tomahawk with 2500km (1,550 mile) range. Both were eliminated as were Soviet equivalents under the Intermediate-Range Nuclear Forces Treaty (INF Treaty) which banned missiles with ranges between 500-5,488km (310-3,410 miles). The US August 2019 withdrawal from the INF has opened the door to renewal of US (and likely Russian) Army strategic missile efforts. It could be suggested the US Army was already pushing toward resurrecting these capabilities possibility anticipating the withdrawal from the INF and responding to the Russian Federation’s road-mobile Iskander-K tactical missile system which US officials insist exceeds the 500km (310 mile) INF range limit.

SRBM
Russia’s Inskander Short Range Ballistic Missile (SRBM) and equivalents such as the PRC Dong-Fang DF-11 and Iranian Fateh-110 can deliver conventional warheads with better than 10 metre accuracy against fixed targets such as airfields, rear areas, and command facilities.

In fact, the US Army has moved quickly to full the perceived gap in what it refers to as mid-range capability. In November 2020 it announced it intended to adapt the BGM-109 Block IV Naval Tactical Tomahawk cruise missile and the latest land attack version of the Naval SM-6 Standard missile for ground launch application. The Tomahawk offers 1,667km (1,035 mile) range, mid-course correction and multiple tracking and homing sensors capable of both land and surface ship attack. The earlier GLCM used a heavy semi-trailer four missile launcher so its feasibility it at least established. Application of the SM-6 in a mobile ground launched configuration is, however, a relatively new endeavour. SM-6 has 556km (345 mile) range, dual seeker, and both external and autonomous targeting direction and is a proven anti-air and anti-missile capability, as well as a recently introduced land and ship target engagement capability. In November 2020 Lockheed Martin was awarded a $340 million contract to build the US Army’s new mid-range missile prototype launcher. A February 2020 Congressional Budget Office study suggested a four-cell truck trailer launcher like the Army THAAD would be feasible, although appropriate complementary radar and missile reloading would also be required.

Seeking to reach even further the US Army is also pursuing development of its Long-Range Hypersonic Weapon (LRHW) give the Army a 2,250+km (1,400+ mile) range strategic conventional strike capability to “defeat A2/AD capabilities, suppress adversary Long Range Fires, and engage other high payoff/time sensitive targets.” LMCO has a $347 million contract to build boosters, guidance and canisters/eight missiles, and modify four trucks to serve as two-missile transporter-erector-launchers (TELs). Live fire testing is planned for 2022. These are at least partly in response to People’s Republic of China’s land-attack DF-17 and anti-ship DF-100 hypersonic missiles which were seen in it its October 2020 parade. However it is likely that the LRHW will be a high-priced weapon that will be reserved for high priority targets and unlikely to be available in quantity. Given this alone, it is less clear when or if these assets would be available for use in counter A2/AD tasks. Therefore, other systems being pursued will be needed.

LRPF adoption

A2/AD is broad challenge facing NATO and other militaries. With more limited resources and equipment and operational constraints these forces may need to be more selective in their pursuit and adoption of long-range precision fire solutions.

The US approaches may not be appropriate. For example, although the US Marine Corps, which has HIMARS and could adopt PrSM, it was pursuing mounting the Navy NASAMs on the lighter JLTV for its longer-range surface strike.

In addition, even armies which have already field the M109 howitzer may hesitate to adopt the US Army’s ERCA until field results are available. They might be also inclined to watch the progress of ramjet projectile development.

by Stephen W. Miller