Introduction

The threat imposed by UAS is manifold as these systems come in various sizes, shapes and applications. This chapter outlines the broad range of threats which derive from UAS as well as the different environments where NATO has to anticipate their use. This chapter will also discuss threats which are unique to un-manned systems, provide adversaries with new options to challenge NATO and require innovative approaches when having to counter them. The chapter concludes with recent examples of UAS activities which were able to breach the security measures in place at the time.

Proliferation of Unmanned Aircraft Systems

Consumer and Commercial Drones

Unmanned systems available as Commercial-Off-The-Shelf (COTS) products range from very lightweight drones of just barely 100 g to small UAS of up to 150 kg.

Consumer drones first went mainstream around 2011 resulting in a vibrant market for hobbyists and photography enthusiasts and they have seen exponential growth since. Current beginner systems which can carry a usable payload, such as a small camera, start at less than a hundred Euros and are literally available everywhere and affordable for everyone, to include Non-State Armed Actors (NSAA) and terrorist organizations.

As an example, the number of drones in Germany alone has more than tripled from 162,000 to over 600,000 since 2015.¹ Although the consumer market begins to look saturated, the commercial drone industry is expected to show stages of growth that will continue to accelerate over the next few years. Analysts estimate that the global commercial drone market will grow tenfold from 4 billion USD in 2018 to 40 billion USD in 2024.²

With the rise of commercial UAS, it can be expected that these drones will incorporate better and more capabilities than consumer versions currently provide. Some of the estimated main markets for commercial systems are agriculture, transport, security and telecommunications.³ These applications will likely require improved payload, sensing, and automated flight capabilities, which may also enhance the potential threat if these systems were misused.

This development should raise concern as NSAA and terrorist organizations are highly innovative in identifying and adapting new technologies for their purpose. Broadcasting propaganda of successful attacks on the Internet helps these organizations to make other terrorist groups aware of new technologies and eventually disseminate them even further.

Some examples of NSAA and terrorist organizations using commercially available drones are, amongst many others, The Islamic State of Iraq and Syria (ISIS), The Houthi Movement, and even drug cartels in Mexico and South America.

The Islamic State of Iraq and Syria. The group purchased drones through multiple different companies in more than seven countries and can be seen as the originator of the terrorist drone threat. With their supply chain, technical human resources, and own research and development activities, ISIS modified commercial drones into airborne Improvised Explosive Devices (IEDs). At the end of their drone programme, ISIS was able to construct its own drones with an approximate payload of 5 kilograms of explosives. Although the organization had lost most of its territory in its former core areas in Syria and Iraq, other NSAA have started to use drones in the scope of ISIS’ drone strategy.⁴

The Houthi Movement. Houthis are evidently more advanced in using technologies than other NSAA. Apart from employing Unmanned Surface Vessels (USV) loaded with explosives against oil trade routes in the region, they also utilize small UAS, allegedly provided by Iran. It has been observed that the Houthis were able to successfully guide artillery fires and missiles with their UAS and hit targets with a level of precision that used to be credited to regular armed forces only.⁴

Drug Cartels. In Mexico, drones have been extensively used for drug trafficking purposes in the region of the Mexico-US border as their use significantly lowers the risk of being caught. The route of the drone is pre-programmed and due to its autonomous capability, it cannot be blocked by electronic jammers at the border. The cartels in Mexico also use so-called potato bombs – hand grenade-sized IEDs – in attacks on each other.⁴

‘Those worried about drone proliferation must face facts. We are no longer in a world where only the US has the technology, and we are not moving toward a future in which the technology is used only in the same way we use it now.’

Peter Warren Singer, Director of the Centre for 21st Century Security and Intelligence at the Brookings Institution

Military Unmanned Aircraft Systems

Multiple extensive reports on military drone proliferation have been published in recent years, showing that at least 95 countries now maintain active military drone programmes. This is a 58 percent increase within a decade, and there are currently at least 21,000 military drones in operation around the globe.^{5, 6, 7, 8}

Apart from the United States, the United Kingdom and Israel being the long-established market leaders in unmanned technology, there are at least 19 countries currently developing or operating military UAS. Amongst these ‘2nd generation’ of unmanned system producers and operators are China and Russia as well as most of the Middle Eastern countries, including Iran. The increasing export of unmanned technology – not only by these states – also raises concerns about the need for effective control on the proliferation of armed UAS.⁷

Russia. There has been much speculation and misinformation regarding the Russian development of armed drones. A large number of armed UAS have been designed and prototypes put on display, only for those models to never be heard of again. However, allegedly disappeared prototypes such as the Voron, Chirok, Skat, Altius, Inokhodyets, Dozor 600 and Proryv-U show that Russia is actively pursuing significant improvement of its military UAS inventory. Notable UAS programmes include the ‘Forpost’, several variants of the ‘Altius’ system and the ‘Okhotnik’ UCAV, which is strikingly similar to Western concepts such as Northrop Grumman’s ‘X-47B’, Dassault’s ‘Neuron’ or BAE’s ‘Taranis’. Zala Aero, which is part of the Kalashnikov Group, offers multiple UAS that cover almost all classes and categories, including systems that are specifically designed to operate in extreme climate conditions such as the Arctic. Furthermore, several Russian UAS are especially adapted to navigating without the use of global satellite-based navigation systems, which are often unreliable in Polar Regions. For that purpose, the drones use a newly developed system, GIRSAM, when GPS and GLONASS are not available.^{7, 9, 10}

China. China has risen to become one of the foremost producers and exporters of armed UAS, with over half a dozen states now operating strike-capable Chinese systems. According to the Stockholm International Peace Research Institute’s (SIPRI) Arms Transfers Database, exports of Chinese ‘Wing Loong’ and ‘CH4-B’ strike capable UAS to Egypt, Iraq, Nigeria, Pakistan, Saudi Arabia and the United Arab Emirates have all been confirmed. Many experts suggest that these UAS are copies of the US ‘Predator’ and ‘Reaper’ and that the components are not of such high specification as their US counterparts. However, they are much cheaper and sell for a fraction of the price of the original US systems, making them attractive for customers in the Middle East and elsewhere, e.g. Serbia. Chinese UAS comprise tactical systems such as the ‘CH-3’ and ‘CH-3A’, Medium-Altitude Long-Endurance (MALE) variants such as the ‘CH4-B’, ‘CH-5’ and ‘Wing Loong’ series, as well as High-Altitude Long-Endurance (HALE) UAS, such as the ‘Cloud Shadow’. Reportedly, all of these systems have similar capabilities if compared to Western UAS, to include BLOS communications via SATCOM, range, endurance, as well as sensor and weapon payloads.^{7, 9}

Iran. Separating actual and on-going UAS programmes from rumoured capabilities and stalled or failed prototypes is difficult. However, despite conflicting reports and regardless of trade sanctions from the international community for a number of years, it can be concluded that Iran has indeed developed and manufactured armed UAS, although there is likely less capability than has been projected by Iran itself. Iran’s primary UAS is the combat-proven ‘Shahed-129’, a roughly ‘Predator’ sized MALE system. It is primarily intended to perform C4ISR missions but can also be employed in attack roles mainly for deploying air-to-surface munitions. The ‘Mohajer-6’ tactical UAS is the most mature version of its series and in 2018 Iran announced that it had entered serial production for the Islamic Revolution Guards Corps (IRGC). The ‘Yasir’ is a small UAS, most likely reverse-engineered from a Boeing ‘Scan Eagle’ which had been captured by Iran in 2012. According to Iranian military commanders during an interview in 2014, the ‘Saeqeh’ UAS was developed with technology obtained from reverse-engineering an American RQ-170 Sentinel, which was allegedly captured by Iran in 2011. If the ‘Saeqeh’ has actual combat capabilities is at least questionable and the system itself may be just part of Iran’s propaganda. However, the risk that potential adversaries were able to exploit and reverse-engineer Western technology should raise concerns that need to be addressed in future systems.^{7, 9, 11, 12, 13, 14}

Non-State Armed Actors. Low, Slow, and Small UAS are already an inherent part of the arsenal of NSAA and terrorist organizations. The proliferation of consumer and commercial LSS UAS with the potential for misuse by these organizations has already been outlined at the beginning of this chapter. However, non-state actors such as Hamas, Hezbollah or the Houthi forces, have reportedly been provided with larger UAS by Iran and other supportive regimes. Conclusively, NATO has to anticipate the employment of larger UAS beyond the LSS spectrum, not only from peer adversaries but also from NSAA and terrorist organizations.⁷

Threat Environments

In contrast to most military disciplines, the challenge of defending against UAS is not limited to a wartime scenario. Rather, a considerable part of C-UAS work will already have to be dealt with as a peacetime task.

Wartime

Not only in a peer-to-peer conflict scenario but also during lower tiers of escalation between parties to a conflict, adversarial use of unmanned systems against NATO forces has to be anticipated throughout the entire range of UAS classes and capabilities. Especially in the early stages of a developing conflict, UAS may be the preferred choice as they do not involve the risk of human casualties, hence they lower the potential for escalation. On the other hand, this may also lower the threshold of UAS employment, which in turn increases the need for having to counter these systems early on.

In wartime, NATO forces can utilize the complete range of combat activities to counter UAS, limited only – as every combat action – by International Humanitarian Law (IHL), the Laws of Armed Conflict (LoAC), and the Rules of Engagement (RoE). This does not necessarily mean that countering UAS in wartime would be easier than in peacetime, but the military portfolio of potential actions is significantly broader – to include targeting UAS ground installations and personnel – and the engagement options are less restricted.

Peacetime

The threat from UAS in peacetime can be almost exclusively narrowed down to consumer and commercial drones whereas at the same time, the threat from larger military systems can be almost neglected, assuming that the regular airspace surveillance is sufficient to deter foreign countries from unauthorized entry into the National Airspace System (NAS).

The main challenge of having to counter UAS in peacetime is not defending the airspace, it is rather the problem of detecting drone threats in the first place, and then securing military installations and critical civilian infrastructure from unauthorized intrusion and potential damage, while at the same time, domestic law typically restricts military activities to a minimum. Depending on the respective national regulations, military countermeasures may not be applicable at all and the entire responsibility may lie with the law enforcement agencies, which, in turn, requires very close civil-military cooperation and coordination.

Finally, the protection and safety of the civilian population takes priority over all defensive measures, which considerably limits the ‘traditional’ options for defending against flying objects. There is simply no acceptable collateral damage in peacetime. Hence, new approaches are required, e.g., to manoeuvre drones to safe locations or to land them in a controlled manner before the final countermeasures can be taken.

General Threats from Unmanned Aircraft Systems

UAS are basically flying platforms which can be equipped with a multitude of sensors and weapons. Depending on their size, this may range from a simple camera up to a full set of guided ordnance on a military system.

Imaging Sensors

The typical sensor on even the smallest consumer drone is a digital camera. However, even non-military UAS, for example, commercial drones used by farmers to monitor their crops and fields can incorporate sophisticated sensors, such as LiDAR (light detection and ranging) or multi-spectral Electro-Optical (EO) cameras. Some of the most relevant imaging sensor types are:

Electro-Optical/Infrared sensors extend from the ultraviolet (UV) through the visible region to the infrared (IR) spectrum. EO/IR systems are depending on the illumination of the target or the target’s emission of light. EO/IR sensors are in general sensitive to the environment and depending on the weather conditions, light may be refracted, absorbed or scattered, reducing the quality of the captured image. However, EO/IR sensors can intensify the light waves received and provide imagery also at night.¹⁵

Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) provide high-resolution imagery independent of daylight, cloud coverage or weather conditions. Through processing, modern SAR systems convert the captured raw data in real-time and provide a perfect vertical view of the target area. In recent years, SAR units have become smaller and more capable as hardware is miniaturized and better integrated, so even smaller systems like Boeing’s ‘ScanEagle’ can provide tactical SAR coverage.¹⁶

Light Detection and Ranging (LiDAR) is a remote sensing method that uses light in the form of a pulsed laser to measure ranges to the surface. These light pulses generate precise, three-dimensional information about the shape of the Earth and its surface characteristics. There are a multitude of civil and military applications for LiDAR such as terrain and vegetation mapping, mapping beneath forest canopy or water surface, creation of digital surface and city models, or forest height and density measurement.^{17, 18}

Multi-/Hyper-Spectrum Sensors. All materials reflect, emit, scatter and absorb electromagnetic waves in a characteristic way. However, only a small portion of this spectrum is visible to the human eye. Military applications include the detection of disturbed soils, which can be an indicator of a buried IED, or revealing the presence of explosive materials. Image processing software can then process the captured image and make the information visible to the human eye.^{19, 20}

All of the aforementioned sensors are not limited to military systems only. Commercial, and to a limited extent also consumer systems, may incorporate these sensor capabilities. Conclusively, NATO has to anticipate that basically every UAS may be capable of capturing thermal signatures, mapping terrain and objects through clouds and beneath forest canopies as well as to detect disturbed soil from, for example, tracked vehicle movements.

The broad accessibility to these sensor capabilities can be considered a game-changer as they transform even commercially available consumer drones into a viable threat to NATO operations.

Weapons

Military UAS such as the Chinese CH-x and ‘Wing Loong’ series, the Russian ‘Altius’ and ‘Okhotnik’, or the Iranian ‘Shahed-129’ are allegedly capable of carrying air-to-ground, and in some cases also air-to-air ordnance.7 For example, the Russian ‘Altius’ is expected to support up to two tons of combat payload,²¹ whereas Iran is said to have dropped multiple Sadid-345 guided bombs on the Islamic State in Syria with their ‘Shahed 129’ UAS.²² However, little is known about these systems’ actual capabilities and NATO should anticipate a level of targeting and precision strike abilities which is comparable to own systems.

Consumer and commercial drones are generally unarmed but can be modified to carry serious amounts of explosives, converting them into an airborne IED. They may also be turned into more nefarious weapons by attaching hazardous material such as a nuclear, biological or chemical payload. Unfortunately, criminal and terrorist ingenuity is almost unlimited and difficult to predict. So even small consumer drones require serious attention as they can have considerable destructive potential if they have been modified accordingly.

Target Acquisition and Indirect Fires

Over the last two decades, NATO and its Allies, especially the United States, have proven the effectiveness of UAS and how significantly these systems contributed to linking sensors and shooters. UAS became an integral part in the sequence of Find, Fix, Track, Target, Engage, and Assess (F2T2EA), also often referred to as the ‘Kill Chain’. This has not gone unnoticed, and other countries are now incorporating similar Tactics, Techniques, and Procedures (TTP) into their own doctrine.

For example, Russian forces have acquired the capability to use numerous layered sensors to feed into their target acquisition cycle, to include multiple UAS platforms – even COTS products – which relay target data to artillery systems for action. This has been demonstrated in Eastern Ukraine where Russian forces direct and adjust fires with their unmanned systems. Ukrainian forces have repeatedly seen a systematic approach by the Russians to acquire a target, determine its coordinates, and adjust their artillery fire with UAS in a total timeframe of about 10–15 minutes.^{23, 24}

The Russian example shows that mimicking proven Western tactics is not a question of expensive military technology. It can be done quite successfully with only consumer and commercial products.

Therefore, NATO has to anticipate that future adversaries, symmetric as well as asymmetric, will be able to employ some form of viable ISR and targeting capabilities utilizing unmanned systems. Consequently, every UAS or drone sighting in the vicinity of our own forces should raise immediate concerns about being spotted and targeted.

Electronic Warfare

Since 2008, the unifying themes of Russian Armed Forces reforms have been asymmetry and the recognition that the means and methods of modern warfare have changed. From Russia’s point of view, its adversaries would seek dominance in the aerospace and information domains, which exponentially enhances the role of Russian Electronic Warfare (EW) to level out NATO’s information superiority.²⁵

‘Relying too much on high-information and electronic technologies made the course and outcome of combat actions increasingly dependent on the condition and functioning standards of computer information and computing networks, knowledge and databases, systems and assets of radio communication, radar, radio navigation used in systems of state and military control, reconnaissance, and control of weapons, particularly high-precision ones.’ ²⁵

Major General Yury Lastochkin, Chief of the Russian Electronic Warfare Force

Although EW systems are mostly mounted on ground vehicles, some variants of Russian and Chinese UAS are allegedly capable of carrying EW payloads to employ them with more agility and at longer ranges than the systems on the ground.

The Russian ‘Orlan-10’, for example, can be equipped with an EW suite as part of the Leer-3 EW system, enabling it to disrupt GSM signals within a radius of six kilometres. In addition, the UAS can imitate a cellular base station, forcing connections from nearby devices, analysing their transmissions and locating their position.²⁶

The Chinese ‘Wing Loong II’ appears to come in a SIGINT variant as well. Pictures of a circular antenna array fitted underneath the fuselage indicate that the system could be capable of intercepting communication signals while providing a bearing of the transmitting signal.²⁷

Unique Threats from Unmanned Aircraft Systems

Swarming

Unmanned systems are typically cheaper than manned aircraft, especially if consumer and commercial products are taken into account. This price advantage creates the opportunity to acquire multiple times more UAS than manned combat aircraft. Grouping together multiple UAS creates a so-called ‘swarm’ and depending on their numbers, they are expected to cause significant challenges for current Air Defence systems. For example, in January 2018, an improvised swarm of ten drones rigged with explosives was employed in a coordinated assault against Russia’s Hmeimim airbase in western Syria. The drones appeared to have been assembled from a small engine, cheap plywood and a number of small mortar shells and were allegedly launched from a site more than 50 kilometres away. Although all of the drones were eliminated or forced to land, this incident has proven that the concept of swarming is a viable threat, even when using improvised devices.^{4, 28}

Autonomy

True autonomy in terms of having a robot or machine making an informed decision by itself has not yet been achieved. However, the technology to create fully automated systems that use pre-programmed algorithms to process the robot’s sensor inputs is readily available. Highly automated systems are typically perceived as ‘autonomous’ because their behaviour is seemingly unpredictable. In fact, it is not the system but the environment in which it operates which is unpredictable, leading to changing sensor inputs and thus, varying actions by the automated system.²⁹

One example of an autonomous UAS is the Israeli Aerospace Industries’ (IAI) ‘Harpy’, an anti-radiation loitering munition that can autonomously home in on radio emissions. The ‘Harpy’ is designed to loiter over the battlefield for about six hours and attack targets by self-destructing into them or returning home, if no target could be engaged during the duration of the mission. China purchased an undisclosed number of ‘Harpy’ drones in 1994 and unveiled a reverse-engineered version of the system, the ASN-301, during a military parade in 2017, which appears to be a near copy of the original.³⁰

Moreover, even today’s consumer products incorporate highly automated functions, such as active detecting, tracking and following of persons and objects, or waypoint navigation with autonomous trajectory calculation and active obstacle avoidance based on the drone’s sensor inputs.³¹

Both categories, commercially available drones as well as military UAS, should be considered ‘autonomous’ in the way that they probably no longer require a permanent command and control link to fulfil their mission. This eliminates many of the current countermeasures which rely on jamming their radio transmissions.

Lower Operational Threshold

Unmanned systems offer three principal advantages over manned systems concerning the operational threshold when projecting military force.

Reduced Risk. Minimizing the risk of losing a human pilot has been the driving factor for developing UAS. Because there is no human on board, there is no casualty if the UA is shot down or captured by enemy forces.

Expendability. Compared to manned aircraft, UAS come at a significantly lower cost. Some tactical UAS, but especially smaller systems, are specifically designed for expendability and some of them are not even considered for reuse.

Less Potential for Escalation. Employing UAS to penetrate foreign airspace and to gather intelligence bears less risk of escalating an emerging crisis as no humans get killed if a UAS is shot down.

These three factors contribute to the fact that the operational threshold for deploying these systems against NATO is likely to be lower than using manned aircraft. Therefore, NATO should anticipate the employment of military-grade UAS already during a developing crisis.

Recent Examples of Unmanned Aerial Threats

Germany, 2013
Drone Crash Landing in Front of German Chancellor

At a campaign rally in Dresden on 15 September 2013, a small quadcopter flew within a few feet of German Chancellor Angela Merkel and Defence Minister Thomas de Maiziere, hovering briefly in front of them before crashing into the stage practically at Merkel’s feet. Fortunately, the quadcopter, a Parrot AR drone, was harmless. The person who was operating the drone from a nearby hide-out was quickly located by the police and briefly taken into custody for being accused of disturbing the event.^{32, 33}

Great Britain, 2018
Closure of Gatwick Airport

Between 19 and 21 December 2018, hundreds of flights were cancelled at Gatwick Airport near London, England, following reports of drone sightings close to the runway. The reports caused major disruption, affecting approximately 140,000 passengers and 1,000 flights. A Sussex Police spokesman said: ‘The incident was not deemed terror-related and there is no evidence to suggest it was either state-sponsored, campaign or interest-group led. Through corroborated witness statements, it is established that at least two drones were in operation during this period, and the offender, or multiple offenders, had detailed knowledge of the airport.’ ^{34, 35}

Venezuela, 2018
Alleged Assassination Attempt on Venezuelan President

On 4 August 2018, attackers used two DJI M600 drones, each carrying a kilogram of C-4 explosive, to reportedly conduct an attack on the Venezuelan President Nicolas Maduro while he was giving a speech at a military parade in Caracas. If confirmed, this had been the world’s first known attempt to kill a head of state with a retail drone, purchased online and manually weaponized with military-grade explosives. However, the legitimacy of the assassination attempt is doubted and various countries asked for an independent investigation.^{36, 37, 38}

Great Britain, 2017
Drone Landing on British Aircraft Carrier

In August 2017, an amateur photographer flew his DJI Phantom across the Invergordon harbour to take some imagery of the Royal Navy’s docked aircraft carrier HMS Queen Elizabeth. When the drone sensed a high wind risk, it landed itself on the flight deck. After taking pictures from the deck, the photographer managed to fly the drone back safely. The pilot was aware he had broken rules on flying too close to the ship and reported himself to armed police guards at the entrance to the shipyard.^{39, 40}

Saudi Arabia, 2019
Attack on Saudi Oil Refinery

On 14 September 2019, Saudi oil facilities were severely damaged by a combined UAS and cruise missile strike which led to the interruption of an estimated 5.7 million barrels of the kingdom’s crude oil production per day, equivalent to more than 5% of the world’s daily supply. The Iranian-backed Houthi rebels in Yemen publicly claimed responsibility for the attack. However, a United Nations’ investigation concluded that the UAS and land-attack cruise missiles used in the attack did not have sufficient range to have been launched from Yemeni territory nor had the Houthis been shown to be in possession of the type of UAS used in the attacks.^{41, 42, 43}

Summary

UAS and drones have proliferated to such an extent, that their use against own forces must be anticipated literally anywhere, anytime and from any potential adversary. This includes both wartime and peacetime and will occur inside and above NATO territory as well as abroad. The capabilities of even consumer drones have reached a more than sufficient enough level of technology to use them as efficient tools for ISR, targeting and directing of fires. Potential adversaries are actively pursuing to mimic Western UAS designs and their respective warfighting tactics and it would be negligent to underestimate their fast-developing capabilities.

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