Nuclear Future: Rethinking the Nuclear Forces in the Days to Come

The key objective of the SNF survival strategy is to ensure that your adversary is compelled to spend much, ideally severalfold, more delivery vehicles and warheads to destroy the smaller number of your weapons. As a result of such first counterforce strike, the attacked country is set to emerge with prevailing nuclear forces. In this approach, preemptive strikes make no sense and classic strategic stability is easy to maintain. Note that inadequate SNF survivability of one side is as dangerous for other sides as it is for itself—in a spiraling crisis, an international actor that feels vulnerable may lose the nerve, attacking first out of fear, to remain defenseless.

Certainly, to say that the nuclear triad has not changed after its full deployment in the early 1960s would be an oversimplification. The “form factor”, so to speak, had been well defined for strategic delivery vehicles, but the capabilities of the internals had been substantially changing throughout the Cold War, both in the Soviet Union and in the United States, with subsequent developments in Russia and China on later stages, and with the U.S. is now reactivating programs to modernize its triad.

The modern edition of the nuclear triad is a long-established system, and when today’s generals at Russia’s Strategic Missile Forces, U.S. Air Force, France’s Force de dissuasion or China’s PLARF were just starting their careers as lieutenants, it was not so different, and even some hardware were the same. Nevertheless, with advancing science and technology (including improvements in other types of weapons) and rising military and political tensions between major powers, business as usual is not an option. Following below is a brief and inevitably superficial outline of the key challenges facing each of the SNF triad components and their potential solutions.

The shifting military and technical environment as well as the revving-up global arms race will call for revolutionary changes across all the SNF components to ensure survivability of national strategic forces. The “demand” for such breakthroughs on the part of the political and military leadership of all nuclear-armed powers will be relentlessly on the rise in the near future.

Last year, we took a brief look at possible alternatives for the evolution of strategic nuclear forces at the dawn of the nuclear era in the 1950–60s. Following a period of “creative experimentation,” the nuclear triad had more or less settled in its classic form, and it has since survived to the present day without any fundamental changes. But this is bound to end very soon.

Certainly, to say that the nuclear triad has not changed after its full deployment in the early 1960s would be an oversimplification. The “form factor”, so to speak, had been well defined for strategic delivery vehicles, but the capabilities of the internals had been substantially changing throughout the Cold War, both in the Soviet Union and in the United States, with subsequent developments in Russia and China on later stages, and with the U.S. is now reactivating programs to modernize its triad.

Alexander Yermakov:
The Nuclear Triad: Alternatives from the Days Gone By

The 1970s saw a proliferation of new type of payloads for intercontinental ballistic missiles (ICBMs), namely called a multiple independently targetable reentry vehicle (MIRV). The development of miniaturized thermonuclear warheads, missile and electronic technology converged into a system that instead of hitting a target with a single warhead could send on a prescribed course a post-boost dispenser stage, commonly known as a MIRV bus, which provided a platform complete with its own engines and a highly accurate control system that could release, at the exact pre-computed time, a bundle of warheads, without propulsion of their own, guided along accurate pathways to engage separate targets. Therefore, one MIRV-carrying missile was capable of striking a dozen targets located hundreds and thousands kilometers away from each other. MIRVs were preceded by simpler but fewer manufactured multiple re-entry vehicles (MRVs) that could propel 2 or 3 warheads with a preset deviation from a central aim point—not so flexible as MIRVs but good enough for taking care of large area targets in countervalue attacks (i.e. against cities). Under the Russian classification, first MIRV-equipped ICBMs are considered 3^rd generation systems of that type, whereas, for example, modern mass-produced “Yarses” belong to the 5^th generation.

Along with land-based missiles, MRVs/MIRVs were fitted onto submarine-launched ballistic missiles (SLBM) that had long been viewed as counterforce weapons due to their lower accuracy—a limitation which has, apparently, been overcome only in the recent decades. The high survivability of their launch platforms—nuclear-powered submarines (SSBN or PLARB ⁱ in the Russian terminology)—contributed to their reputation of the “weapon of assured retaliation.” That became a particularly fitting description when SLBMs’ range was extended to intercontinental distances, from the mid-1970s in the USSR (R-29 / SS-N-8 Sawfly) and from the late 1970s in the United States (UGM-96 Trident I). Now, there was no need for nuclear submarines to penetrate antisubmarine barriers on their way to potential launch areas as they could comfortably patrol their own secure waters in the near maritime zone (200–500 miles from the coastline), though it has always been tempting, especially for Americans with their advantageous alliance geography, to keep some of the submarines “at a pistol shot”.

Another approach taken by the USSR to bolster the survivability of its strategic delivery vehicles in case of the enemy’s counterforce attack was to use road-mobile transporter-erector-launchers (TELs), or mobile ICBMs. The rationale was that mobile platforms dispersed in the period of threat across a wide deployment area (which in Russia often has the benefit of forest canopy cover that hinders detection even from space and to some extent cushions the effects of nuclear explosion) would require the attacking party to use up radically more warheads to assure their destruction. The first unit entering operational service in 1976 was RS-14 Temp-2C, a limited number of which were produced. Its direct descendants include the TEL truck carrying the RSD-10 Pioneer medium range missile and the modern systems well known to anyone with the slightest interest in weaponry: RS-12M Topol, RS-12M2 Topol-M, and the RS-24 Yars family (note that a significant number of Topol and Yars missiles are deployed in underground missile silos). Largely inspired by the Soviet and Russian school of thought, China, too, is now busy developing its own TEL fleet to address survivability concerns regarding its strategic nuclear forces (SNF). Beijing’s first fully mobile ICBM platform was DF-31A, which first came into service in the late 2000s. A couple of years ago, China also fielded heavier MIRV-armed DF-41 missiles. North Korea has its mobile ICBM program as well, although its systems with large liquid-fuel missiles have limited mobility that merely allows them to drive out of their underground shelter into the open to fire off from a level ground nearby.

Notably, no other nuclear power, including the United States, has so far developed its own ICBM-capable TEL system. The closest the U.S. came to having their mobile platform was the MGM-134 Midgetman, a project aborted in 1992 for obvious reasons after one successful test launch. Its conceptual design and actual construction are very different from the classic design of Soviet, Russian and Chinese missile trucks (with their massive tubular missile container atop of a heavy-duty multi-wheeled chassis). It will be discussed later, along with its Soviet quasi-equivalent, the Courier system.

Russian Ministry of Defense
Topol-M test launch

A derivative mobile concept is an ICBM launch system mounted on railway cars or on rail-mobile ICBM platforms. Such systems were also deployed exclusively by the USSR/Russia with heavy solid-fuel RT-23 Molodets (SS-24 Scalpel) missiles from 1987 till the end of the missiles’ service life in the early 2000s. The United States considered creating a rail-based Minuteman ICBM as early as the 1960s (for details, see the previous article), but its best and nearly completed effort by the end of the Cold War was the Peacekeeper Rail Garrison program (designed to carry the LGM-118 Peacekeeper missile), which had to be scrapped much like the Midgetman. A more thorough discussion of the strengths and weaknesses of rail-mobile systems can be found in a separate publication.

The 1980s brought a revolutionary transformation for the triad’s airborne leg when gravity bombs and bulky cruise missiles, as the primary nuclear armament, were replaced by small-size hard-to-detect high-precision cruise missiles, the American AGM-86B ALCM and the Soviet Kh-55 (AS-15 Kent), featuring the kind of designs we are more accustomed to seeing today. In addition to the much smaller size and weight allowing for several-fold bigger carried weapon loads, the new cruise missiles offered high accuracy targeting from an impressive range (over 2000 km). The new comers brought the cutting edge back to the triad’s air-force component, which had steadily been slipping into obsolescence. At the same time, missiles with similar performance specifications were adopted by the navies, with submarine fleets being the first in line. Nuclear Tomahawks and Granats (SS-N-21 Sampson) were installed on both multipurpose and the less numerous special purpose submarines carrying land-attack cruise missiles (LACM),ⁱⁱ enabling both types of submarines to attack both coastal as well as remote inland targets with high precision and almost undetected. Incidentally, provided that the USSR had developed such submarines ahead of the United States,ⁱⁱⁱ it is rather odd to hear the statements made more than once by the Russian leadership about “the unfairness of the INF Treaty that fails to account for sea-based cruise missiles.” However, this fuzzy status of being halfway between strategic and conventional weapons proved to be quite a hassle, stalling the development of nuclear weapons of this class for political reasons. Under the “Presidential initiatives” of Bush, Gorbachev and Yeltsin, the two governments agreed not to arm vessels on patrol duty with non-strategic nuclear weapons. In the early 2010s, the United States retired its remaining nuclear-capable Tomahawks altogether. The feeble attempt made by the Trump Administration to launch a replacement project has ended with the shutdown of the SLCM-N program this year. There is a widespread view that Russian Kalibr missiles are indeed existent and deployed in nuclear configuration, but the lack of data regarding their number, basing modes and role in the military doctrine leave much room for speculation.

The modern edition of the nuclear triad is a long-established system, and when today’s generals at Russia’s Strategic Missile Forces, U.S. Air Force, France’s Force de dissuasion or China’s PLARF were just starting their careers as lieutenants, it was not so different, and even some hardware were the same. Nevertheless, with advancing science and technology (including improvements in other types of weapons) and rising military and political tensions between major powers, business as usual is not an option. Following below is a brief and inevitably superficial outline of the key challenges facing each of the SNF triad components and their potential solutions.

The Land Component: Challenge of Vulnerability

In the modern world, the land-based strategic nuclear capability only includes missiles installed in hardened underground silos and on transporter-erector-launchers (TELs), remaining an integral part of the arsenals maintained by the three top nuclear powers out of the “Legitimate Five”^iv (the United States, Russia, and China) and by all the four “illegal” nuclear weapon states (Israel, India, Pakistan, and North Korea).

Russian Ministry of Defense
Directed-energy weapon Peresvet

Underground silos offer a host of benefits: fewer restrictions on size and weight when it comes to missile design, higher accuracy thanks to the pre-established coordinates of launch points, relatively simple and inexpensive construction, maintenance and operation, the shortest command-to-launch time (as fast as several minutes to flash down the entire chain of command when on high alert), and representing the biggest share of the warhead inventory constantly available to launch at short notice.

With all the mesmerizingly superior merits, their high vulnerability has been “the Sword of Damocles” hanging over the land-based forces from their inception. Early ICBMs were installed on open pads—not unlike the familiar launch sites for space rockets (in fact, both space and military delivery vehicles in those times were often modifications of the same designs)—but it quickly became obvious that such facilities were highly exposed even to enemy’s low-accuracy ICBMs, especially considering the high nuclear yields that were the common remedy of the day for poor accuracy. Nuclear early-warning systems and reaction spans were inadequate for protecting ICBMS by counter launch. Once it became operationally possible, missiles were stored in hardened underground silos which, given their widely scattered locations, required a near-bull’s-eye hit to destroy and, as a consequence, preferably two warheads aimed at each silo.

The concept got less reliable with the advent of MIRV-armed ICBMs. The attacker, using missiles with three or more submunitions, had good chances to wipe out all the silos without spending all of its warheads, which is the definition of a successful counterforce strike when the attacking party is left with considerably more delivery vehicles and warheads than its adversary, allowing the attacker to blackmail the disarmed country with further strikes against cities using the remaining firepower.

In very simple terms, the key objective of the SNF survival strategy is to ensure that your adversary is compelled to spend much, ideally severalfold, more delivery vehicles and warheads to destroy the smaller number of your weapons. As a result of such first counterforce strike, the attacked country is set to emerge with prevailing nuclear forces. In this approach, preemptive strikes make no sense and classic strategic stability^v is easy to maintain. Note that inadequate SNF survivability of one side is as dangerous for other sides as it is for itself—in a spiraling crisis, an international actor that feels vulnerable may lose the nerve, attacking first out of fear, to remain defenseless.

Responding to the deployment of the opponent’s MIRVed ICBMs, the Soviet Union opted for mobile platforms, wheeled-chassis and rail-mobile ballistic missile systems. Their mobility and camouflage prevent the adversary from obtaining reliable positioning data, and their destruction requires barraging the enemy with a severalfold bigger number of warheads. However, the advancement of space surveillance technology along with data processing and control systems (including machine learning and big data technologies already proven in civilian applications) could, even in the short term, severely compromise the classic mobile ICBM concept, which is essentially built around “juggernauts” like Topol, Yars or DF-41.

US Department of Defense
Prototype of the road-mobile TEL with the small MGM-134A Midgetman

This is not a matter of visibility. While KN-11 KENNEN satellites could detect strategic missile trucks way back in the Soviet era, data transmission and processing still incurred substantial lags in reaction, and the few available satellites, equipped with sufficient detection capability, could only track narrow strips of land across the enormous Soviet territory. So, continuous monitoring of all mobile ICBMs in all operational areas was out of question, and the several-hours-old positioning information is practically useless for targeting. Another important factor to remember was that the side with mobile ICBMs would have been sure to employ a range of camouflage and concealment methods in the period of threat (not the mere camouflage netting thrown over parked vehicles, but, for instance, various aerosols with special properties) as well as to know satellite passing times in advance.

Today, the situation is totally different. Apart from the obvious change in data processing speeds, a fundamental transformation has occurred in space: the “eyes” have not become much sharper, but vastly more numerous, which is even a bigger threat to survivability of mobile platforms. The revolutionized space launch market and the progress in microelectronics empowered even private operators to shoot entire constellations of satellites into orbit, providing remote sensing services. For example, Planet Labs has over 200 satellites in orbit—most of them, of course, providing low-resolution imagery of circa 3 meters/pixel, but its fleet also includes about 20 SkySats capturing ground data at 50 cm/pixel. Maxar, on the other hand, operates a few WorldView satellites that can provide imaging data on par with military-grade systems in terms of resolution (as high as 30 cm/pixel). These are just two Western firms out of a legion that are certainly willing to cooperate with the Pentagon. The latter is also building the new National Defense Space Architecture (NDSA), an unprecedented constellation of many hundreds, expanding in the future to thousands, of small coordinated satellites with diverse functionality, including surveillance. In this context, the current decade is probably the last when the United States is still unable to threaten the states, which rely on classic mobile ICBMs, with its capability to continuously monitor the positions of missile trucks of the opponent. Besides, this threat could potentially be augmented with hypersonic high-precision conventional missiles.

Surely, more advanced camouflage, active countermeasures to disable satellite optics with laser systems like the directed-energy weapon Peresvet—here, shooting satellites down could also be helpful—but there is a danger of being drawn into a self-obsessed wild goose chase after the ever-eluding survivability of classic mobile ICMB systems while completely forgetting that mobility is only a means to an end. A method that has its flipside: mobility has always come at a price, both in terms of money (mobile systems are way more expensive to produce and even more so to operate) and in terms of readiness as the land-based ICBM fleet inevitably has a smaller share of launch-ready missiles as compared to underground silos as well as a longer reaction span.

AFA library
MPS Concept

In a situation where classic ICBM TELs are losing their primary advantage, there are two obvious solutions. Number one would be to scrap them altogether, putting focus on silo-based options (even Russia has never given up silos that are now used to store most Topol-M’s and a considerable number of Yars ICMBs, let alone heavier vehicles). In this case, the progress of space reconnaissance technology would no longer make any difference (in this particular application), whereas the following silo-specific strengths could be leveraged to boost survivability:

• Far better protection against a nuclear explosion or a high-precision conventional strike. In fact, destroying a silo requires a direct hit by a small to medium yield nuclear warhead or a super-surgical strike with a high-precision long-range conventional missile, while it has to be specifically designed to penetrate such targets. Legacy silos are increasingly hardened up thanks to the smaller new-generation missiles that free up more room inside for added reinforcement.
• Significant ease of setting up launch site missile defense both to impede targeting (with a combination of jamming, aerosols and decoys) and intercept high-precision conventional missiles or even ballistic missile warheads using short-range active missile defense systems. The task is much simplified because the aim point coordinates are known in advance, and no warhead can destroy a silo if activated at considerable altitudes. Hypersonic gliders are even more vulnerable on the terminal flightpath than the faster and smaller warheads of standard ICBMs.
• Lower cost (money and man-hours) of manufacturing, deployment and operation, and a much higher, nearly absolute, share of the missile inventory continuously available on high alert. No “headaches” associated with extensive counter-sabotage measures (counter-mine, air defense, etc.) to protect TEL batteries marshalled into columns. More reliable and simple communications and control management.
• Zero threat of losing most of the arsenal at home bases as a result of an enemy’s sudden attack, unless mobile ICBMs have been moved to dispersed positions in advance, and no need to mobilize all strategic missile battalions into the “field” (a tactic best avoided, as it can fuel escalation).
• The shortest command-to-launch time; the best way for a missile to survive an enemy strike is to get launched first.

With easy-to-provide defense capability and a bigger share of ready-to-launch inventory, underground ICBM silos may offer a somewhat better survivability performance than the classic road-mobile systems, as these are easy to detect and are relatively vulnerable. This may not be the case, however, with regard to mobile platforms of a conceptually different type.

Faster or Deeper

AFA library
Subway 1.5 meters deep launch system with ICBM

To get some tentative insight of possible alternatives for the future evolution of mobile ICBMs, it would make sense to look back at some projects dating back to the Cold War. Many of them are still around, like hypersonic gliders that originated from the R&D programs of that time. Unlike Soviet projects, on which we have relatively scarce data to go by, we know significantly more about American efforts. For the subject in question, it would be best to consider a program to develop a mobile land platform for the small MGM-134A Midgetman and discussions of platform options for the LGM-118A Peacekeeper (also known as MX).^vi

The former is an interesting case of an essentially different mobile design compared to the Soviet missile truck family that had evolved into a classic concept adopted by China and North Korea. Americans planned to use a specially designed lightweight single-warhead ICBM with a launch weight of only 13.6 tonnes (for comparison, Minuteman-III weighs 36 tonnes while the weight of Yars is about 46 tonnes). With corresponding throw-weight sacrifices, the small ICBM could be fitted onto a relatively compact Hard Mobile Launcher (HML) that, due to its geometry and robust construction, was good at surviving the effects of nuclear weapons. For additional protection, shortly before an expected attack, the HML truck could lower its body onto the ground, partially ploughing itself into the soil. Although this would be a far cry from the security of an underground silo, the truck was able to withstand an explosion of a medium-yield MIRV warhead at a distance of 1–1.5 km (wherever possible, of course, the HML crew would also take advantage of rugged topography, etc.).^vii This is a fairly long distance to dash, but—given the smaller missile weight—the HML should have been able to drive at 45–60 km/h on unsurfaced roads.

With a Midgetman HML randomly based in a deployment area (or with at least more than 15 minutes warning time for garrison-based HMLs in garages on high alert), the attacker, even knowing its location at launch time, would have had to barrage the area with a disproportionate number of warheads for an assured target kill^viii. Today, however, the “dash to disperse” tactic, which used to be preferred over “moving shelters”, has been undermined by the increased threat of hypersonic terminal-homing missiles or externally-guided munitions (for example, with satellites providing targeting data).

Another, more radical, option is to go completely underground, dramatically reducing the effectiveness of surveillance. During the early development of the MX ICBM basing plans, the principal option was the random basing by moving mobile launch platforms between twenty three shelters/launch sites via underground tunnels (Multiple Protective Shelter, MPS concept) connected by a 24-kilometer loop, nicknamed the “racetrack.”^ix In peacetime, and especially so at a time of threat, transporters were supposed to keep Soviet reconnaissance teams busy by continually reshuffling the MX launchers and decoys between shelters, thus presenting multiple aim points, all of which would have to be targeted in case of a strike. A different concept proposed a little earlier was that of a buried trench or missile subway 1.5 meters deep using self-propelled unmanned missile launch vehicles.^x Each missile would run in a twenty-kilometer-long tube, moving randomly between fully concealed potential launch points spaced at every half-mile where missiles could be launched after erecting the container right from under the ground. Each flight (group) of missiles was to be controlled by a mobile launch control center with a two-person crew. Considering that the trench system would be hardened, tortuous and fitted with blast-restraining plugs, the attacker, even knowing the trench layout, would have to blow up a vast area to hit all the missiles.

U.S.-designed underground projects of the 1970–80s never made it off paper, largely because of prohibitive costs,^xi and the projects of rail-mobile Peacekeeper and land-mobile Midgetman HML that had just moved into execution, were terminated after the collapse of the Soviet Union. Sure enough, the Soviet Union had also been pondering further development of mobile ICBM platforms. Today, we know much less about those conceptual designs, and among the projects that progressed all the way to the “hardware” phase, the most intriguing was what would be the Soviet answer to the Midgetman – the RSS-40 Courier with a lightweight ICBM.

militaryrussia.ru
Prototype of the RSS-40 Courier

Options considered at the early stage of the project included deployment in standard cargo containers mounted on box-truck chassis.^xii In a period of threat, RSS-40 trucks would be randomly run on public roads, with their survivability enhanced by camouflage. This approach has its downside (the need to manage security on patrol routes and exposure of civilian infrastructure to potential nuclear attacks), especially in the modern world and with new surveillance and data handling technology, but it could hold some potential as an improved version of “dispersing mobile launchers.”

The shifting military and technical environment as well as the revving-up global arms race will call for revolutionary changes across all the SNF components to ensure survivability of national strategic forces. The “demand” for such breakthroughs on the part of the political and military leadership of all nuclear-armed powers will be relentlessly on the rise in the near future. The U.S. harbors plan to first deploy their upcoming LGM-35A Sentinel ICBM, developed under the Ground Based Strategic Deterrent (GBSD) program, in existing silos, but they do not rule out adding mobile options in the future. Similarly, time will show what new Russian systems, Kedr and Osina, are going to be like. What is known so far is the continued silo and mobile basing configurations, but the latter will not necessarily follow the usual design. China has commenced operational deployment of its DF-41 ICBMs on mobile launchers and is believed to be constructing several “missile fields” simultaneously consisting of several hundred silo facilities.

The evolution of the air, sea and other SNF components will be discussed in upcoming publications.

ⁱ. Under Soviet and Russian classifications, this type of submarines, apart from the earliest models, has been traditionally designated as RPKSN (literally, Strategic Purpose Underwater Missile Cruiser). A more generic designation, commonly used to describe non-Russian submarines, is PLARB, which translates as Nuclear Submarine with Ballistic Missiles and corresponds to SSBN in the US Navy classification.

ⁱⁱ. S-10 Granat system with a KS-122 (3M-10) subsonic small land-attack cruise missile (LACM), not to be confused with P-700 Granit naval anti-ship hypersonic cruise missile. Granat is the direct precursor of the modern Kalibr missile system.

ⁱⁱⁱ. Shortly before its dissolution, the USSR had modernized four 667AT Grusha SSBNs (previously designated as the 667A Navaga project), each armed with 32 strategic cruise missiles, well above the maximum missile capacity of American submarines until the 2000s, when four Ohio SSBNs were converted to SSGNs with an extended capacity to carry 154 cruise missiles.

^iv. From 1971 to 1996, France had a limited number (18) of land-based nuclear missiles deployed in silos. Strictly speaking, those S2, and later S3, were MRBMs, not ICBMs, with a range of 3000 to 3,500 km, but from the French geopolitical perspective they represented strategic weapons that were sufficient to effectively attack the European part of the USSR.

^v. Strategic stability is a balance of relations and strategic forces between two nuclear powers that eliminates incentives for either of the sides to launch the first nuclear strike.

^vi. As an example, see the declassified MX Missile Basing Report (1981) https://ota.fas.org/reports/8116.pdf

^vii. According to available data, HML strength was assumed to withstand at least 30 psi, equivalent to a 300 kiloton blast at a distance of about 1.3 km. Increasing the yield would be ineffective in this case, e.g. assured HML destruction at 2 km will require over 1.2 megatons, another good illustration showing that MIRV is a more effective solution for most targets.

^viii. According to the report (see below), with HMLs randomly based across the deployment area and at least a 15 minute warning, the attacker will have to spend eight 0.5 megaton warheads per each mobile Midgetman; also note that the estimate does not explicitly account for the time to process surveillance and transmit targeting data. Art Hobson, “The ICBM Basing Question,” Science & Global Security 2/, (1991): 153–198 https://scienceandglobalsecurity.org/archive/sgs02hobson.pdf

^ix. Steven Pomeroy, An Untaken Road: Strategy, Technology, and the Hidden History of America's Mobile ICBMs, (Naval Institute Press, 2016), 171–174

^x. Pomeroy, op. cit., 157–160

^xi. Curiously, one of the biggest headaches for the United States government was the need to buy up huge tracts of land (as a single plot) from private landowners, a ridiculous situation from other countries’ perspective. Even for the existing silos, the government had reduced the purchased land patches to the bare minimum so that now these strategic facilities are literally surrounded by local farmers’ grazing cattle.

^xii. Note that as the project moved forward the missile weight and dimensions increased and absolutely required a special chassis design (though much more compact than Topol carriers). It does not mean, however, that the missile dimensions couldn’t have been reduced with further system evolution.