Center for Arms Control, Energy and Environmental Studies

The Threat of the Use of Small UAVs by Terrorists: Technical Aspects

Eugene Miasnikov's presentation at the International Seminar on the Law of Armed Conflicts, French Air Force Academy, Salon-de-Provence, France, April 7, 2011

It is an honor and pleasure to be here with you today. I am grateful to organizers for such an extraordinary opportunity.

I was asked to tell about one of research projects carried by our Center in the past. The results of the research were summarized in the report "Threat of Terrorism Using Unmanned Aerial Vehicles: Technical Aspects" that was published seven years ago. The report was also translated into English, and as far as I am aware of, it is going to be published in French also. Possibly, some of you are familiar with it.
Threat of Terrorism Using Unmanned Aerial Vehicles: Technical Aspects

Today I'd like to revisit the problems discussed in the report and address the following questions:

To some of you UAVs may seem too exotic, demanding substantial efforts and costs compared with the methods terrorists already frequently use. One may also argue, though there were a few attempts to use UAV technologies for terrorist purposes, none of them, fortunately, proved to be successful.

I agree with these arguments. It would be a mistake to overplay the threat of terrorist's UAVs. Certainly, it is not the top item in the threat priority list these days. Nevertheless, I believe that the threat exists and it will eventually grow.

Let me suggest, that when we talk about threats from terrorist's UAVs, we need to think in broader terms. In my view, there is a fundamental problem that makes the subject of my talk timely and important. Science and technology is developing so fast these days that a human society often fails to recognize how much the world has changed. Appearance of new technologies and public services brings us more opportunities, but at the same time it makes us more vulnerable. Therefore, our society often misses a chance to react to emerging threats in a timely fashion. And, I am worried, this might become a case for UAVs, unless we recognize the threat and take preventive actions.

What consequences terrorist's UAV attacks might have?

Evidence suggests that the objects of terrorist attack and the most vulnerable targets are often places crowded by people: mass gatherings, highly populated city areas, public transportation at rush hour, etc. Terrorists usually pursue two goals: maximizing the number of victims and creating chaos and panic.

It is interesting that payload of UAV does not have to be large to produce significant damage.

This is especially true with regard to weapons of mass destruction. Experts frequently note that an aerial vehicle is an ideal tool for delivering a biological or chemical weapon. For example, the results from simulating an attack with anthrax show that, if 900 grams of weapons-grade anthrax was dropped from a height of 100 m just upwind of a large U.S. city, 1.5 million people would become infected. Even with the most aggressive medical measures that can realistically be taken during an epidemic, the model estimates that 123,000 people would die.

Appreciable damage, though not so massive, could be caused by the most frequently used weapon of terrorists: a mix of explosives with small metal parts. An explosive device, delivered by a UAV to a place crowded by people, could inflict much more damage than the same device on the belt of a suicide terrorist.

Let me give an example of one terrorist attack that occurred on July 5, 2003 near the Tushino airfield in Moscow, where a rock concert was going on. Fifteen people were killed and over fifty injured as a result of the attack.

The bombs, which were carried by suicide women (so called "shaheed belts"), consisted of 0.5-1 kg explosives mixed with 2 kg of small fragments (metal balls, screws, etc.). This composition was not optimal to ensure maximum efficiency, since both terrorists evenly distributed the mix of plastic explosives and metal fragments around their waists in order to hide the deadly load. As a result, one bomb did not work as expected. Only its detonator exploded, killing only the terrorist.

The expert who investigated the case suggested that the electric detonator of the bomb was coupled with a small fragment of the explosive, weighing about 30 to 50 grams, and the rest of explosives were separated from that fragment with a layer of metal balls. Thus, only the detonator and a small part of explosives worked, and the whole device did not explode.

The second explosion occurred among a crowd of people who were standing in line at the ticket office. Most of those who suffered were standing close by the terrorist. They acted as a "live shield" for people who stood behind them at a distance of few meters. Had the same bomb been set off from a UAV at an altitude of few meters, the geometry of dispersal of the metal parts would differ, and the number of victims would have been higher. Fragments of the UAV and remaining fuel might have caused additional damage.

As investigation of the case showed, the terrorists intended to enter the airfield, where many people had gathered for the concert. Perhaps they expected that the explosions would create panic among the spectators, and a crush would occur. History demonstrates many cases in which a high death rate from explosions, fires, or other accidents can be explained by panic among the victims. However, police cordoned off the entrance to the concert and inspected the audience thoroughly. In addition, mobile communications were shut down immediately after the terrorist act in order to prevent panic among the audience. Thus the audience had no idea what was going on beyond the cordon. If a UAV had been used, such measures would have been useless.

These examples illustrate some possible consequences from UAV use in terrorist attacks, but certainly the spectrum of possibilities is much broader.

The fact that even small payloads can cause significant damage may lead to the conclusion that the most likely threat may occur from mini-UAVs. The most worrisome situation stems from model aircraft, where uncontrolled access to the knowledge, skills, and equipment required for mini-UAV assembly exists. Modelers are currently able to assemble vehicles with capabilities that used to be achievable only by professional teams.

Not only are production-run accessories and separate parts such as engines, radio controls, servos, flight stabilization systems, and GPS receivers currently available commercially, but a wide spectrum of ready-to-fly aircraft kit models are on the market. Some models require experience in piloting, but other aircraft that are simple and stable in flight are produced specifically for beginners. Therefore, relatively simple designs that are stable in flight may be used.

UAV control and delivery to a target is a more complex task, but this task is not beyond power of nonprofessionals. The most important element-preparation of an aerial vehicle for a terrorist attack, including assembly and tests-can be done legally, because such activity is not regulated or controlled.

What features of mini-UAVs may make them attractive to terrorists, as weapon delivery tools?

Terrorist attack preparation can be covert. There is also a great amount of flexibility in choice of a UAV launch site.

Terrorist attack preparation can be covert

UAV flight time can be very short even at relatively significant ranges. Existing air defenses have very little capabilities against low-flying UAVs if any in scenarios like shown on the slide.

UAV flight time can be very short even at relatively significant ranges

Model aircraft built by amateurs demonstrate surprisingly sophisticated capabilities. Especially remarkable was the flight of a 5-kg TAM-5 aircraft model across the Atlantic.

The TAM-5 model started from Canada, conducted the flight in automatic mode, and landed 39 hours later 3,000 km away in Ireland.

TAM-5 flight

In order to illustrate the point, that the range of aircraft can be quite long, let me also show calculations for maximum range of a model aircraft made for Lanier Edge 540T model airplane. This model has a fuselage length of 2.1 m, and wingspan roughly of 2.3 m. Its empty weight is about 7.7 kg.

Lanier Edge 540T model airplane specifications

Estimates were made for three cases: a "light" aircraft that carries no payload, a "heavy" aircraft (payload weight is about 3 kg), and a "heavy" aircraft with the same payload and extra drag. The results of the calculations are shown on the slide. You can see that even at a high speed of about 40 m/s, aircraft can reach a significant range of more than 500 km.

Maximum range vs speed

There might be some additional arguments why terrorists might choose UAVs as delivery means:

What needs to be done to prevent terrorist's UAV attack in future?

Apparently, investing into air defenses is not the right answer. The main accent of dealing with the threat of terrorist UAVs needs to be on preventive measures. Some regulations and restrictions do exist, but frequently we face the situation when these restrictions become obstacles either to do good things or they can be easily circumvented.

I think we have a classical situation here. The same instrument can be used for good and bad purposes. One may use a mobile phone to communicate with your friends from almost everywhere. Terrorists frequently use it to set off their deadly devices. Mini-UAV is a great instrument to bring young enthusiasts in aviation and engineering. At the same time, UAVs can be the tools in wrong hands.

I believe the key to the answer is educating the culture. There is a role here for all of us - aviators, teachers, military and scientists. Police and security forces also have a role. But they are unlikely to be able to prevent terrorist's UAV attacks in isolation from the society. At least the public should be made aware of the threat and its potential consequences.

Since the commission of the report, frankly, the focus of my attention was shifted away from UAVs to other research projects, and I did not have much time to closely follow the events. However, just recently, I learnt that my report did cause some consequences.

Surprisingly, RC airplane model hobbyists posted in the Internet a copy of an order signed by a Deputy Chief of one of the regional branches of the Ministry of Internal Affairs of the Russian Federation. The order was issued on July 29, 2008 four years after my report first came out. As you can see, the names, signatures and some other details of the order were removed by those who posted the copy in the Internet. Perhaps, this indicates that the order had a stamp like "For Official Use Only."

However, the content of the order was intact. The order states that:

This was really very unusual for my colleagues and me. We knew that our reports were noticed by governmental agencies. But I can not remember another example of a document issued by a governmental agency in Russia that would make a direct reference to the results of our research.

The order requires the department for public security

I can only guess what the scale of the action was. Was it a one time action or proposed measures are practiced on regular basis? Did the action actually help in preventing terrorist acts or it became counterproductive? Unfortunately, answers to these questions are beyond of my knowledge.

Finally, let me ask you to spend another three minutes to watch a video that was posted by RC model hobbyists in YouTube. I think the video significantly contributes to my arguments. Authors of the video flew their model airplane in New York City. I hope, you might also enjoy watching nice views of Manhattan, its bridges and the Statue of Freedom from a bird's eye distance.

Let me stop here. I'd be glad to take your questions. Thank you for your attention.

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Center for Arms Control, Energy and Environmental Studies, 2011.