Dr Sidharth Kaushal and Dr Matthew Harries
Intercepts of Russian missiles in Ukraine suggest that, although it still has a broad range of nuclear options, Moscow’s ability to carry out theatre-level conventional and nuclear coercion may face complications – particularly if NATO is able to implement a more robust integrated air and missile defence capability.
Recent claims by Ukrainian authorities that six Russian KH-47M2 Kinzhal missiles were intercepted by a Patriot missile defence system in an attack on Kyiv led to a flurry of excitable commentary about the potential implications for Russia’s nuclear forces. Much of this is overblown. Russia has many options to conduct a limited nuclear strike if it so wishes, and neither Ukraine nor NATO’s missile defence capabilities could be confidently expected to simply prevent a Russian attack.
Nevertheless, the successful intercept of at least one Kinzhal, alongside the larger number of verifiable interceptions of Russian cruise missiles such as the 3M-14 Kalibr, does pose interesting questions for Russia’s approaches to both conventional and nuclear coercion at the theatre level. In particular, it suggests that better integrated air and missile defence (IAMD) could allow NATO to complicate Russia’s ability to use conventional precision strike and non-strategic nuclear weapons to manage escalation and compensate for conventional military weaknesses.
What We Know
To be sure, we should be cautious about overstating the significance of the intercept. Though described as a hypersonic missile, the Kinzhal does not meet the standard of manoeuvrability at hypersonic speeds that has led other systems – such as the Chinese DF-17 – to be seen as qualitatively new capabilities. The missile is of the same family as the 9M723 aero-ballistic missile which is launched from the Iskander system. However, it still represents a challenging target for missile defence systems. In contrast to traditional ballistic missiles which fly on a parabolic trajectory, Kinzhal’s quasi-ballistic trajectory represents a more complex target for air and missile defence systems to track. Early in the conflict, it became apparent that the 9M723 is capable of deploying six decoys, which complicate the task of target discrimination in the missile’s terminal phase, including by mimicking things such as the radar return of the missile’s warhead. Given that the two missiles are nearly identical, this could be true of the KH-47M2, although the air-launched Kinzhal may also exploit its greater velocity to carry a larger conventional warhead, which uses up more space.
The likely intercept of at least one Kinzhal by a Patriot battery is thus noteworthy in certain regards. Though PAC-3 has demonstrated considerable effectiveness against short-range ballistic missiles in recent conflicts, achieving a very high intercept rate against ballistic missiles fired by the Houthis against Saudi Arabia, questions have remained regarding its effectiveness against more complex targets. In particular, doubts remain regarding its ability to achieve effective target discrimination when performing terminal-phase intercepts. Failed intercept attempts against Houthi Burkan 2H missiles during the war in Yemen were presumed to be a consequence of the failure of the system’s radar and the seekers on its interceptors to discriminate the missile’s separating warhead from the debris of its body. If the Kinzhals intercepted deployed decoys, as similar missiles such as the 9M723 have, this would suggest the effectiveness of the millimetric wave seeker on the PAC-3 interceptor at discriminating targets from clutter. Moreover, in its terminal phase, the family of missiles is claimed to have a speed of 2.1 km/s – well over Mach 5. Of course, if not carrying decoys then in certain ways a missile like the 9M723, which does not have a separating warhead, is a simpler target for interception for a system like Patriot.
There are caveats to bear in mind, however. First, the Patriots defending Kyiv were performing point defence over a target which it was known the Russians would prioritise – the city itself. Point defence against a missile like the Kinzhal in its terminal phase, though far from easy, is somewhat simpler than performing an intercept in its midcourse phase, when it is manoeuvring on a quasi-ballistic trajectory. As such, the ability to defend a specific target from the Kinzhal may not be illustrative of the ability of air and missile defence systems to provide wide-area coverage against such systems. In a conflict against Russia, some likely targets for Russian missiles will be well known – for example, major airbases and combined air operation centres. Other targets, however, such as command posts for ground units or components of national energy grids, will be more geographically distributed, and if a strike was not for purely tactical-operational purposes but had broader aims in mind – as could be the case in the event of nuclear use – Russia would have a broad range of targets to choose from. Moreover, we are still working with a small empirical base, and will require more reliable evidence that the Patriot is consistently effective against missiles based on the 9M723.
Nonetheless, the event is particularly notable in conjunction with what we know about Ukraine’s intercept rates against Russian cruise missiles such as the 3M-14 Kalibr. While they struggled initially, by the end of 2022, Ukrainian air defenders were intercepting 70–80% of the cruise missiles fired by Russia. This is despite the fact that cruise missiles were used against a relatively wide range of targets and were manoeuvring in flight to confound assessments of their ultimate destination. If air and missile defences can deliver high intercept rates against Russian cruise and ballistic missiles, many of which are dual-use – and especially if these rates differ significantly from pre-war Russian expectations – this could have significant ramifications for both conventional and nuclear coercive strikes.
Implications for Russia
This could have considerable impacts on both Russia’s planning for strategic conventional strike operations (otherwise known as ‘strategic operations for the destruction of critically important targets’, or SODCIT) and its low-yield nuclear options – two things that are closely interrelated in Russian thinking. Russian strategists show a preference for the use of conventional precision strike assets such as cruise missiles to deliver calibrated damage against an opponent, with nuclear weapons playing a passive enabling role by constraining an opponent’s retaliatory options. There is a body of Russian literature on the use of limited numbers of nuclear weapons to deliver ‘dosed’ damage against an opponent if this fails. To the extent that this model of use and subcomponent objectives such as demonstration and intimidation are predicated on the assumption that relatively limited numbers of strike assets would be needed to achieve each mission – which is of particular salience with respect to nuclear use – this assumption will now come into question.
It could, of course, be argued that little has changed for Russia. The costs of layered IAMD remain prohibitive; one expert at the 2023 Air and Missile Defence Conference estimated that the costs to the US of protecting Guam alone would be in the range of $5 billion. While it is possible to erect a missile shield over a specific area such as Kyiv, scaling missile defence across a theatre will be much more difficult, and Russia has a variety of targets that it can strike for demonstrative purposes. Furthermore, given the scale of the missile threat faced by the US in the Indo-Pacific, it is unclear that large numbers of US systems – currently the backbone of alliance IAMD – will be available to NATO in the medium term. Ukraine, moreover, operated 250 surface-to-air missile systems at the war’s outset – the largest air and missile defence force in Europe, and one which was augmented by Western systems.
Air and missile defences capable of intercepting single targets across the European theatre create requirements for Russian planners which militate against the logic of limited nuclear use
That being said, there are potential lessons regarding the implications of a more robust European IAMD capability. The evidence from Ukraine does not necessarily suggest that point defence is the only achievable option. Missiles such as the Kalibr have been used against a wide variety of targets, and Ukraine’s ability to achieve relatively high intercept rates against them in a fairly large theatre is noteworthy – especially since cruise missiles carry the bulk of Russia’s low-yield throw weight. Defending a large theatre against ballistic missiles like the 9M723 and the Kinzhal would prove much more challenging, of course, but these missiles are fewer in number. Moreover, the relative success of Saudi air defenders against Houthi short-range ballistic missiles illustrates that ballistic missile defence (BMD) over a large theatre is achievable.
To be sure, realism should inform our assessments. There is no plausible and affordable NATO IAMD system which can defend every inch of alliance territory against Russia. Moreover, if Russia intended to use low-yield nuclear weapons to play on fears of subsequent escalation in order to achieve a peace on its terms, then it would not be constrained to attacking targets of military or strategic value; a demonstration almost anywhere would have the desired effect, and striking at some distance from anything of significance might be useful as a means of signalling restraint.
However, there are two important ways in which Russia’s strategic posture – including elements of its approach to nuclear use – would be impacted by more credible NATO IAMD.
First, air and missile defences capable of intercepting single targets across the European theatre create requirements for Russian planners which militate against the logic of limited nuclear use. The question is not one of whether Russia can be prevented from striking targets with low-yield nuclear weapons, but whether it can be prevented from doing so in a way that allows it to credibly signal limited intent. To signal this and thus avoid unintended escalation, Russia can only mate a limited number of warheads to their missiles and, moreover, must launch limited salvos.
Second, Russia also intends to use low-yield nuclear weapons on a much greater scale when a conflict escalates to the level of a large-scale war. For example, one of the performance criteria set for the Russian Navy by the country’s 2017 Naval Doctrine is the ability to do critical damage to an opposing fleet using non-strategic nuclear weapons. Such weapons would also likely be used in a regional war to target critical infrastructure such as airbases, which are difficult to shut down permanently using conventional capabilities. To the extent that Russia believes it needs larger numbers of missiles to achieve its aims at this level of warfare, this imposes constraints on the Russian system when a conflict is in its conventional phase. Every missile used for a conventional mission is one that will not be available for non-strategic nuclear use, and the production rates of ballistic missiles like the Iskander – roughly six a month – suggest this will be a major constraint. To be useful, NATO IAMD does not need to deny Russia the capacity to conduct low-yield strikes, but rather it needs to increase the number of missiles Russia requires in order to conduct these strikes, thus constraining its options for conventional targeting.
While it is highly likely that Russia will remain capable of saturating the air and missile defences of well-defended targets, it can be compelled to do so in ways which will require expending ever-greater numbers of dual-use missiles. This would particularly be the case in a potential conflict with NATO. While it might be noted that systems such as Patriot provide fairly limited coverage, for many longer-range air and missile defence platforms, a major limiting factor is not the range of interceptors but that of radar. Networking maritime IAMD platforms or even systems like Patriot with the F-35 – as the US has in recent experiments – can readily increase their range. Maritime BMD capabilities such as the Aster-30 Block 1NT have a theoretical range of 600 km. If combined with external sensors – be it F-35 or a space-based sensor layer along the lines envisioned under the PESCO Timely Warning and Interception with Space-based TheatER surveillance (TWISTER) project – such interceptors could provide wide-area coverage against manoeuvring ballistic and quasi-ballistic threats. Though unsuited for defence against Russia (something they were not built for), the European Phased Adaptive Approach sites at Deveselu and Redzikowo could theoretically be modified to control a larger number of vertical launching systems and to contain a different mix of interceptors, much in the way an Arleigh Burke destroyer at sea would.
To be sure, this is predicated on a level of capacity and integration that does not currently exist within the alliance, particularly in the case of its European members. Several points are salient here. First, the eventual success of projects such as TWISTER remains to be seen. Second, the level of integration needed to deliver results comparable to those achieved by F-35 and Patriot working in tandem may or may not be viable across an alliance which fields a number of air defence systems. Finally, achieving a level of rationalisation across air forces that would allow some to prioritise missions such as defensive counter air – while a prerequisite to any credible IAMD – may not be politically feasible.
While the process of overcoming these barriers exceeds the remit of this article, the important point here is that strategic effects can be achieved by improvements in IAMD well short of a preclusive defence of Europe against Russian missiles.
The Impact of Better IAMD on Russian Strategy
To be clear, there is no plausibly affordable air and missile defence system that can cover Europe against Russian attack. However, an effective IAMD system capable of raising the number of missiles Russia needs to use to strike any given target could hinder elements of Russia’s strategy for missile use.
Improvements in European IAMD could potentially require Russian plans for limited nuclear use to involve greater numbers of weapons, complicating assumptions about escalation management
First, if larger numbers of missiles are needed to strike assets that are likely to be on NATO’s critical asset list and defended asset list, then Russia will need to consider whether the operational utility of striking a target with conventional options – its preference – exceeds the cost imposed in terms of running down capabilities needed to maintain Russia’s nuclear credibility at the theatre level.
Second, Russia could lose some confidence in the idea of a nuclear ‘shot across the bows’ as a tool to manipulate escalation in a reasonably controllable way. The premise of such an attack would have been that striking a high-value target with a missile precise enough to be detonated above the fallout threshold would enable nuclear demonstration at relatively low cost to civilians, thus limiting the risk of escalation. If, however, multiple missiles are needed to saturate a given target, then controlling escalation becomes considerably more difficult. For example, if NATO IAMD can draw data from a space-based sensor layer, then in order to use short- and intermediate-range ballistic missiles, Russia first has to neutralise the satellites associated with projects such as TWISTER. In all likelihood, Russia might also believe it has to suppress any maritime BMD capabilities that NATO has at its disposal. Russia has struggled to replace the Soviet-era Tselina and Legenda satellite clusters, which used electronic signals intelligence and radar respectively to track carrier battle groups. Moreover, even China, which maintains a much more robust space-based ISR network, would have a difficult task tracking mobile maritime targets at very long ranges to the degree needed to enable conventional targeting. Finally, very large numbers of missiles would be needed to sink well-defended air defence destroyers. Russia could turn to the old Soviet palliative – the use of nuclear missiles at sea. Anti-ship missiles like the SSN-19 Shipwreck were built to be nuclear-armed, reducing the need for granular targeting and requiring fewer missiles to leak through to destroy high-value targets. The challenge, however, is that if nuclear missiles are needed to destroy or incapacitate targets such as air defence destroyers, this necessitates nuclear use on a larger scale.
Finally, if penetrating credible air and missile defences necessitated larger salvos, this could in turn require larger numbers of warheads to be mated to missiles, something likely to be noted by NATO intelligence. Unless Russia was willing to run the risk of failure, leading not only to embarrassment but also likely to serious consequences, these steps would defeat one of the prerequisites of calibrated nuclear use: the ability to communicate intent clearly to an opponent. Attacks on space-based assets would create some ambiguity regarding whether Russia was intent on destroying or disrupting early warning capabilities and thus preparing for a larger strike. Russia could mitigate this risk by targeting systems like the US’s planned hypersonic and ballistic tracking system or a comparable future European system in low Earth orbit, while avoiding early warning systems in geosynchronous orbit. The effectiveness of this distinction would depend on Western interpretation, however – something the Russians could not count on given how uncertain such assessments can be. We might think of how Western adversaries, real and simulated, responded in unanticipated ways during exercises such as Proud Prophet and Able Archer.
This problem is compounded for Russia by two factors. First, the majority of the delivery systems for low-yield nuclear weapons are cruise missiles, against which interception rates have been especially high. The exceptions to this rule – the 9M723 and the Kinzhal – are available in more limited numbers. For example, it is estimated that Russia’s monthly production rate for the 9M723 is around six per month. Moreover, of the two missiles, only the Kinzhal is capable of striking targets beyond 500 km. Second, many of the launch platforms for low-yield delivery systems like the Kalibr are surface vessels which are vulnerable to early destruction. This is also potentially true of Russia’s strategic bombers, which can be targeted on the ground at the few airbases from which they operate – though this would certainly not be easy, given the dense air defences around these bases.
Russia can use submarine-launched ballistic missiles (SLBMs) such as the Sineva to conduct low-yield strikes, and it has apparently developed low-yield warheads for the Sineva. The speed of an SLBM on a depressed trajectory means it is all but certain to be effective. However, at this point it becomes all but impossible to signal strategic restraint, or to ensure that an opponent can discriminate a Sineva carrying a low-yield warhead from a loadout of strategic warheads. Moreover, using SLBMs for non-strategic missions means eroding Russia’s strategic deterrent vis-á-vis the US.
Russia’s Options
None of this should be taken to suggest that Russia cannot conduct low-yield strikes in Europe – the country’s arsenal of low-yield capabilities is too large and robust, and the range of potential targets is too broad. But improvements in European IAMD could potentially require Russian plans for limited nuclear use to involve greater numbers of weapons, complicating their assumptions regarding escalation management. The assumption that nuclear weapons can be coordinated artfully with diplomacy is likely to be increasingly problematised.
Additionally, Russia would need to be more judicious in its use of dual-use missiles for conventional strike missions, if a larger number of missiles are needed for many sub-strategic nuclear missions. This, in turn, would constrain Russia’s options for conventional countervalue targeting. Cumulatively, this could have the effect of pushing Russia towards the nuclear doctrine it espoused in 1999, when that year’s Zapad exercises involved the early and large-scale use of low-yield nuclear weapons against a putative opponent (likely NATO). The balance depends, of course, on whether the success rate differs from what Russia, NATO and Ukraine would reasonably have expected, a question which cannot be definitively answered based on open sources. But it should at least give cause to question some of the assumptions about what a Russian conventional missile campaign or ‘limited’ nuclear strike might look like, which have been common in public discourse since the beginning of the war. In particular, a Russian attempt at ‘limited’ nuclear use against NATO might be more complicated than feared, but – were it to occur – it would be more escalatory and even more potentially damaging than is sometimes hoped.
The views expressed in this Commentary are the authors’, and do not represent those of RUSI or any other institution.
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