Soft-kill and maritime air defence: A systems approach

With low-cost drones and missiles threatening even well-defended naval assets, this analysis examines a systems approach to integrating electronic warfare that could rebalance the cost equation.

Recent experience of naval combat in theatres such as the Red Sea and Black Sea has illustrated several challenges which navies will face with respect to air and missile defence. First, modes of attack against naval vessels are orders of magnitude cheaper than the interceptors which are often employed against them. For example, the cost of a UAV such as the Samad-2 or a Shahed-136 can be measured in the thousands of dollars.^[1] Even more expensive systems such as the now widely proliferated Chinese C-802 missile are comparatively cost effective, with the C-802 costing around USD 500,000.^[2]

This poses several challenges for navies. In addition to the obvious issue of cost asymmetries between threat and countermeasure, a rapid rate of expenditure of air defence interceptors will challenge fleets’ operational tempo. As has been seen in the Black Sea, where Ukraine was able to successfully attack the Russian Black Sea fleets headquarters within the heavily-defended bastion of Sevastopol with Storm Shadow cruise missiles, even well defended military facilities will be at risk close to the theatre of combat.^[3] This, coupled with the fact that vertical launch system (VLS) replenishment at sea remains difficult, will mean that vessels which have expended a large portion of their loadout will need to be rotated to often distant bases for replenishment, limiting the endurance of a fleet in-theatre.

In this context, the ability to engage low-cost targets with systems other than air defence interceptors is of considerable importance. Electronic warfare (EW) capabilities offer particular promise in this respect. Against targets such as UAVs which often use commercial-grade guidance and communications systems, EW capabilities can achieve considerable results. Although steps have been taken by many nations to reduce vulnerabilities, for example by placing some sensitive components within Faraday cages, there are still a number of means of electronic attack which can prove viable against UAVs. In a similar vein, the active seekers of many older cruise missiles, which are not equipped with millimetric wave seekers, are vulnerable to a range of electronic countermeasures (ECM).

None of this is exactly new and EW has been an integral component of naval combat for decades. However, soft-kill systems are still largely employed as either a means of augmenting traditional hard-kill air defence systems, or as a last-ditch defensive capability. The employment of hard- and soft-kill capabilities in an integrated manner, rather than merely in tandem with one another with a marked preference for the former, will be important if navies are to manage the risks posed to them by modern air threats.

The present approach and its pitfalls

There are a number of soft-kill capabilities deployed by navies as things presently stand including shipboard ECM suites and decoys such as the Nulka Digital Radio Frequency Memory (DFRM) system. What is absent from navies today is not capable existing systems or in-house expertise, but a concept of operations (CONOPS) that integrates hard- and soft-kill components together, rather than treating them as separate but complementary capabilities.

As an example of the phenomenon described we might consider the 2016 attack on the USS Mason by Ansar Allah (the Houthis). The Mason engaged a salvo of two C-802 cruise missiles launched by the Houthis with a combination of two SM-2 missiles and ESSM and two Nulka decoys. While the outcome was that the Mason was unharmed, the crew appeared to have been initially uncertain as to whether the missiles were engaged by the Mason’s SAMs or diverted off course by the Nulka decoys employed.^[4] All this would appear to indicate that all possible hard- and soft-kill measures were employed in tandem to maximise the prospects of engaging the missile. This approach, while reasonable against a small number of targets, is unviable against a larger target set. This would correspond with what is known about the workflow in the combat information centre (CIC) suite of a naval vessel where Anti-Air Warfare officers and EW supervisors operate in relative isolation from one another despite operating within the same CIC suite. To be sure, a principal warfare officer (PWO) serves an ultimate coordinating function, but given the compressed time horizon available and strong incentives to employ capabilities which achieve a demonstrated effect (such as missiles), the PWO’s incentive structure is likely often biased towards overkill rather than sufficiency.

In theory, an optimal system would be one in which missiles which were being successfully engaged with soft-kill capabilities were removed from the target list of hard-kill air defence. This is, of course, difficult to achieve in practice, not least because some forms of successful electronic attack (such as deceptive jamming) do not necessarily provide visible evidence of success until late in the trajectory of an attacking system. At that point, if success has been misjudged, the outcome can be catastrophic. Nonetheless, there are potential pathways to rendering hard- and soft-kill capabilities more complementary than is currently the case.

A zonal approach

One approach might involve the creation of zones of responsibility, with soft-kill means used first, and threats engaged with hard-kill assets only if they have crossed a given point. This is challenging under current circumstances because EW capabilities often form a final defensive layer rather than an outer zone. For example, the Nulka is launched on a rocket out to a few kilometres from a vessel, while towed decoys such as the AN/SLQ-49 are even closer to the target ship when deployed.^[5]

The deployment of EW capabilities, however, could be an immediate role for uncrewed surface vessels (USVs). While the employment of USVs as combat systems capable of holding, for example, vertical launch systems is likely to take some time, many USVs could in principle hold a decoy such as Nulka which, given its relatively efficient thermal battery, would not necessarily draw a great deal of power from the USV’s propulsion system.^[6]

Another avenue might be the employment of lower-cost converted civilian vessels for tasks such as barrage jamming. A great deal has been written about the potential value that the containerisation of missiles might add to navies as they seek to increase their launch capacity.^[7] This is true but another avenue for the employment of civilian vessels would be to utilise their large powerplants to generate the energy needed to power barrage jamming capabilities. Barrage jamming involves an emitting vessel to generate signals on multiple frequencies within a likely spectrum of adversary activity to quite literally drown out useful emissions. Its major disadvantage is that it is highly power-intensive and thus, since range and required power are inversely correlated, difficult to achieve over long ranges. It is also typically a risk to the vessel employing this approach, as it can be readily detected by hostile electronic intelligence (ELINT) and targeted by anti-radiation missiles (ARMs). Large, lightly-crewed vessels which are relatively low-cost might be an optimal platform for barrage jamming capabilities.

The more navies can rely on offboard platforms which can provide EW on a persistent basis at longer distances, the easier it will be to rationalise the employment of SAM systems by allocating them zonally to missiles which cross an outer belt of EW capabilities.

Subdivision by Threat Type

An alternative approach would be the subdivision of allocated assets based on the type of threat detected. Although vessels are challenged by a spectrum of aerial capabilities in the maritime domain, these capabilities can be differentiated based on characteristics such as speed, altitude and trajectory. UAVs, for example, employ considerably different trajectories to cruise missiles.

Given that a major part of the challenge of scale is the threat posed by UAVs, this threat could be one to which EW and close-in weapons systems (CIWSs) were exclusively allocated. On the one hand, UAVs are often particularly susceptible to electronic attack, particularly when they rely on commercial inputs. Moreover, as relatively slow-moving targets, they are more susceptible to gunfire and CIWSs in their terminal phase. Finally, the consequences of a strike with a one-way attack (OWA) UAV with a much smaller payload than the average cruise missile (a Samad-2 has an 18 kg warhead, and by comparison a C-802 has a 165 kg warhead) are considerably lower meaning that some risk can be accepted with respect to close in defence.^[8]

An approach which relied on the subdivision of capabilities based on threat type, with a focus on soft-kill and close in weapons against UAVs would, however, depend to a significant degree on accurate classification. While this is possible based on the characteristics described, there is a risk that an opponent who understood one’s targeting approach would employ cruise missiles on higher-altitude trajectories in salvos timed to ensure that faster-moving cruise missiles caught up with slower-moving UAVs to converge on a vessel. The use of fast- and slow-moving targets is something which is discussed by China’s PLA for example.^[9] This level of coordination is likely to elude many sub-peer opponents, however.

However there may also be technological fixes. For example, airborne sensors both on traditional airborne early warning and control (AEW&C) aircraft and reconnaissance UAVs can help with target discrimination. The discrimination of targets is also an area where artificial intelligence (AI) can be of utility. A mature application of AI is the discrimination of different types of target, something which neural networks built around the principle of accepting bias to reduce variance and thus classifying phenomena based on relatively limited key fragments of data, are very well suited to if properly trained.^[10]

Integration

The most radical approach would be to strive for genuine integration between soft- and hard-kill capabilities. This would require a few changes at both the organisational and doctrinal levels. We might, for example, consider the consolidation of the EW petty officer and anti-air warfare officers’ roles under the aegis of a single effects coordinator whose work was overseen by the PWO.

Consolidation has its risks to be sure – EW and air defence are both specialised functions which justify specialised roles allocated to each task. However, while operation of systems is a specialised role, the supervision and resource allocation need not be as highly specialised. The supervision and coordination of both functions could be performed by a single officer other than the PWO. An effects coordinator specifically tasked with allocating either EW, hard-kill, or both if necessary, to a given task would represent a means of rationalising their employment relative to a system in which both processes run in parallel.

The integration of the software packages underpinning both EW and air defence would also represent a logical step were this approach to be taken, since operators across both EW and air defence would need to be aware of which threats were being allocated to each type of system.

Conclusion

The scope and scale of air and missile threats to vessels at sea provides a considerable incentive for the creation of more synergies between the soft- and hard-kill systems on naval vessels. There are a number of approaches to achieving this, from those which focus more on divisions based either on zonal or altitudinal criteria to those which involve a genuine integration of organisations and functions.

Dr Sidharth Kaushal

 

 

[1] Nakissa Jahanbani et al. Iranian Drone Production is Scaling Up and Turning More Lethal. Warontherocks. September 8, 2023. https://warontherocks.com/2023/09/iranian-drone-proliferation-is-scaling-up-and-turning-more-lethal/

[2] James Holmes. Is the US Navy a Sitting Duck?. Foreign Policy. October 25, 2016. https://foreignpolicy.com/2016/10/25/is-the-u-s-navy-a-sitting-duck-yemen-houthis-china/

[3] BBC. Ukraine Hits HQ of Russia’s Symbolic Black Sea Navy. BBC.22 September 2023. https://www.bbc.co.uk/news/world-europe-66887524

[4] Sam LaGrone. USS Mason Fired 3 Missiles to Defend From Yemen Cruise Missiles Attack. USNI. https://news.usni.org/2016/10/11/uss-mason-fired-3-missiles-to-defend-from-yemen-cruise-missiles-attack

[5] BAE Systems. Nulka Active Missile Decoy. https://www.baesystems.com/en-aus/what-we-do/nulka

[6] ibid

[7] TX Hammes, R. Robinson Harris. Warship Weapons for Merchant Platforms. USNI Proceedings. February 2025. https://www.usni.org/magazines/proceedings/2025/february/warship-weapons-merchant-ship-platforms

[8] Army Recognition Group. Analysis: Houthis arsenal used against Western ships in Red Sea. https://armyrecognition.com/focus-analysis-conflicts/army/analysis-defense-and-security-industry/analysis-red-seas-arsenal-houtis-delivers-missiles-against-western-vessel#:~:text=Its%20flight%20range%20is%20about,a%20warhead%20weighing%2018%20kg.&text=The%20Samad%2D3%20drone%20differs,charge%20can%20reach%2040%20kg.

[9] James Holmes and Toshi Yoshihara. Red Star Over the Pacific: China’s Rise and the Challenge to US Maritime Strategy. (Annapolis: Naval Institute Press, 2018) p.248

[10] See Ajay Agarwal, Avi Goldstein, Jason Goldfarb. Prediction Machines: The Simple Economics of Artificial Intelligence.( Boston:Harvard Business School Press, 2018)