War in cities and the protection of civil population: how space technologies can help?

Communication delivered at the occasion of the “War in Cities” study day organized by the ICIR, the Belgian Red Cross and the Belgian Group of the International Society for Military Law and Law of War, 20 April, 2023.

Today, 55% of the world’s population lives in urban areas, a proportion that is expected to increase to 68% by 2050, depending on the estimation considered. According to the Department of Economic and Social Affairs of the United Nations, if we look at the less developed regions (excluding China), the total population will be multiplied by a factor 7 from 1950 until 2050. Urban areas are key to sustainability for many reasons. For instance, it is merely unknown that cities generate more than 75% of the global GDP. Every week, the global urban population increases by about 1 million. Every day, urban areas expand by an area equivalent in size to 20,000 football fields?[1]. These are only few examples that help to explain why the world needs a deep and accurate scientific knowledge of the way cities will evolve. Social and economic transformations linked to this growing urbanization will not only generate revenues; they will also contribute to more waste, ecological damages and conflicts. Monitoring these trends will require space technologies. In the framework of this short article, a more specific focus will be placed on urban conflicts and the protection of civil population in these contexts.

Urban warfare is usually considered as the archetype of those asymmetrical, non-permissive and highly contested environments in which Western-modelled military forces are facing the greatest challenges. In Sun Tzu’s famous book, The Art of War, it is said that the “worst policy is to attack cities”. In urban warfare, from a military point of view, it is difficult – if not impossible – to find any centre of gravity to concentrate attacks. Moreover, any action that needs to be engaged largely differs from the mass, superpower-led “Air-Land” battle type of engagement.

To put it clearly, this kind of engagement has always represented a black hole in the technology-centred approach adopted by Western militaries?[2]. Although information superiority can offer a critical advantage, reliance on space-based assets appears to be extremely difficult in the urban environment.

Indeed, one might be tempted to say that space-based technologies are ill adapted for the monitoring of urban environment and its population in time of conflicts. This is partly true. Lessons learned, new and more responsive space capabilities, new emerging technologies and advanced algorithms, combined with the growth of digital technologies among the populations are the elements that have to be taken into consideration as they helped to develop new strategies and more appropriate means to monitor building destructions, to protect the civilian population and to engage the necessary re-foundation of critical infrastructures and services in the aftermath of a conflict.

By definition, space-based assets are a dual-use family of technologies. And it goes far beyond technology. Of course, when we talk about space, we think of launchers, satellites, receiver terminals, guided weapons systems. The space ecosystem, especially in the context of urban warfare monitoring and mitigation, is far more dense and complex. It encompasses dedicated personnel, services, infrastructures… not only from the military, but also from the civilian/commercial community.

Some characteristics of urban warfare

In urban warfare, the environment is the greatest “equalizer”. It allows an unarmed enemy to challenge a far more advanced and powerful military force. The complexity of the terrain offers an enemy bunkers capable of resisting bombs, but also allows him to use guerrilla tactics to defeat armies. Certainly, technology still plays a major role. That’s why new technologies are needed and are developed for this very special type of combat. To adapt or use tools that were originally designed for other environments is not the answer. Moreover, space-based systems alone cannot be considered as the panacea: they have to be combined with other technologies, resources and methods of investigation.

Urban contexts also pose unique challenges related to protecting civilians and ensuring their access to critical services. Urban warfare have devasting effects for civilians, especially when parties to a conflict fail to respect the relevant rules of international humanitarian law (IHL) regulating the conduct of hostilities. As you certainly know, in the context of fighting in cities, even basic occupations or activities expose the civilian population to danger. They have to avoid sniper fires, they are exposed to attacks on their homes, schools, and places of work. Combat in cities may forces them to leave their homes in search of a safety place. As a result, warfighting in cities systematically imply massive displacements of people.

The very complex nature of urban environments create many difficulties not only for the soldiers, but also for the rescue teams and the NGO to intervene at the right place at the right time. For the military, planning and targeting are particularly important due to the proximity of the civilian population. In an ideal world, operational planning should allow the military to be compliant with rules of engagement before engaging the forces against any objective. The use of multiple sources of intelligence and other forms of expertise can ensure more precise targeting and reducing negative impacts on the civilian population. Space-based assets can therefore contribute to these goals, while some inherent limitations to their use should be taken into consideration.

In the following sections, I will attempt to explore the contributions of satellite technologies to urban combat and the protection of civilians. I’ve chosen to especially focus on the contribution of satellites systems to the protection of civilian population. While evoking the advantages of these technologies, I will also explore the limits of space technologies in these different scenarios.

Geospatial intelligence

Of first importance is the use of satellites for intelligence, surveillance and reconnaissance missions that offers the soldiers and the rescue teams unique capabilities to have a global picture of the situation of the theatre?[3]. The great advantage is that electro-optical satellites – in the same way that all satellites – can operate independently of airspace restrictions. Analysis of satellite imagery can often provide independent and compelling evidence in direct support of war crime investigations?[4]. The use of satellite imagery not only complements traditional field investigations, it can also have an enhancing effect, improving the planning, quality and accuracy of field work.

Indeed, there are many circumstances under which on-site field investigations of reported human rights and IHL violations and population monitoring are not possible due to insecurity, government/combatant prohibitions on travel, or inaccessibility of an area. Under these circumstances, electro-optical satellite imagery has proved to be one of the only viable means of planning for team’s deployment and assistance. Satellite imagery has also proved to be of rapid and systematic identification, verification and documentation of possible exactions in situations where NGO teams, observers could not be on the field.

There are, however, a number of technical limits, analytical challenges, and political restrictions to the application of imagery for rescue purposes and IHL verification missions in urban environments. These limits have to be considered and understood properly.

An obvious limitation of electro-optical satellite sensors is that they simply cannot see through clouds. For instance, in the case of a conflict occurring within cities that are located in regions concerned by the monsoon season, sustained cloud cover can prevent the use of electro-optical sensors to provide detailed analysis of the conflict.

However, an increasingly viable alternative source of satellite data exist: it is the new generation of radar sensors (also known as “synthetic aperture radars” - SAR). These do not have the same weather-based limitations. SAR sensors actively map or illuminate the ground using radar; the derived data can be easily acquired at night, even through heavy clouds.

Investigative applications resulting from SAR sensors are of particular interest?[6]. They include, for instance:

• Mapping infrastructures as roads, bridges, which can help rescue and assistance teams to plan emergency responses in the case of damage to these infrastructures;
• Defining the critical infrastructures that need to be preserved or protected during the conflict with – when it is possible – the cooperation of belligerent parties;
• Detecting potential weapons caches, hideouts and other structures;
• Locating large concentrations of displaced civilians as well as the monitoring and the geolocation of protagonists’ conventional military forces within the city?[7]; However, it should be mentioned that parties to the conflict can rely on concealment and camouflage techniques in order to escape from satellites coverage.

Despite the numerous advantages in capability, the practical application of electro-optical or SAR data – this time taken together – for research by civilian institutions and NGO either on potential violation of international humanitarian law or on protecting the civilian population from strikes and destructions can be limited by several – and sometimes unexpected – limitations.

• A first limitation is the complexity of radar signatures making interpretation and processing methods uneasily by analytical teams.
• A second limitation is the availability of improved skill personnel. Indeed, it appears that analysts who possess the required specialized skills are generally heavily concentrated within national military and intelligence agencies. Far less specialists are available for civilian research and investigation teams. This is even more problematic as it must be underlined that detailed imagery analysis can often result in ambiguous, inconclusive, and even politically contested or erroneous findings. Analysts can make mistakes, come to widely divergent conclusions about the same image.
• A third limitation results from the dual-use legal agreement underpinning the operation of very high-resolution SAR sensors. The data issued from these sensors is potentially subject to political restrictions over sensitive areas.
• A fourth limitation encountered is that very high-resolution satellites (that include both electro-optical and SAR sensors) do not collect imagery automatically and continuously over the world. Rather, they are tasked over specific and very delimited areas with known political, military or humanitarian value. Consequently, unreported and unanticipated conflicts in remote areas can easily go undocumented by sensors for weeks, even months at a time. As a result, little or no relevant evidence are detectable or acquired.
• A fifth limitation especially concerns civilian satellite sensors. These are characterized by lower resolution capabilities. While civilian satellite sensors may have a greater availability, these are far less adapted to identify and track the movement or actions of irregular or poorly armed insurgent groups. It is even more difficult to track units that do not deploy conventional platforms readily detectable from space.

Geolocation in closed environment

For ground troops and rescue teams, geolocation through GPS satellite constellations is an essential and natural support in an open environment. Geolocation, however, has a number of weaknesses as it may be sensitive to decoy or interference. Accuracy is not always guaranteed and signal availability may be lacking. In closed environments, these shortcomings are even more critical: GPS signals are often unreliable, especially because of urban canyons, built spaces, underground or ruins.

As a result, space systems do not necessarily represent the best value for the troops and the rescue teams operating in a dense urban and populated environment. To put it differently, space technology has to be combined with other types of technologies in order to operate as an effect-multiplier. Many alternative technologies can be used in order to offset the inherent limitations of satellite systems. Accelerometers and gyrometers can be used to estimate orientation, speed and position. The great advantage of such devices is that they are completely insensitive to interference. A second solution is magnetic-inertial navigation. This technology uses magnetic field disturbances in addition to the accelerometer technique. However, the paradox of this solution is that this device requires a regular positioning recalibration based on GPS resources.

The need for “technological fusion”

As we can observe, any given technology presents both interesting perspectives and challenging limitations. This is the reason why the military as well as the organizations tasked with the protection of civilian population in cities in war rely on a “technological mix”… at least when the possibility exist to combine space-based infrastructures with other technologies that are either more or less relying on space assets or totally outside this field.

First example, LIDAR technology. Although satellite imagery is limited in its ability to identify the use of prohibited weapons systems, LIDAR technology offers an interesting alternative. LIDAR (Light Detection and Ranging) technology was not originally developed for military purposes or rescue and protective missions. And when it comes to investigate about the use of prohibited weapons, LIDAR sensors are of particular interest for they can detect biological warfare agents and toxic gases in the atmosphere of a specific area.

While electro-optical and SAR sensors prove to be interesting assets in order to map the infrastructure and help identifying people displacements, night-time light imagery from the Defense Meteorological Satellite Program (DMSP) Operational Line-scan System (DMSP – OLS) satellite data can be used in order to detect large refugee movements. Another example of satellite support for damages monitoring is the imagery from IKONOS and JERS helping analysts to count the number of refugee tents in order to estimate the population at risk fleeing from destroyed urban centres. In Europe, the Copernicus constellation is expected to be used for security monitoring missions. Some programmes developed in order to extend the possibilities provided by the constellation include urban monitoring and urban area characterization.

As regards to population monitoring, it is a common place to say that estimating average population numbers and distributions at high-spatial resolution is particularly difficult. Moreover, measuring dynamic population sizes and densities is even more challenging. Yet, to be able to measure population movements following a crisis can also guide rebuilding efforts and can help to take the necessary actions in order to prevent disease transmission, for instance. For this purpose, the fusion of mobile phone date with other sources of intelligence – SAR, LIDAR, GPS – is of particular interest as it allows to have a dynamic view of the city’s population [8, 9].

Finally, I previously mentioned the lack of skilled experts for the analysis of imagery resulting from remote sensing satellites. Today, machine learning and advanced algorithms have proved to be very useful for war destruction monitoring, especially in the context of urban warfare. Once again, the comparative advantage of ML and advanced algorithms lies in their ability to differentiate and categorize different types of building destruction, from those resulting from natural disasters (which are very concentrated zones of destruction) to those caused by weapons systems and intentional bombings. Obviously, any comparative advantage implies some limitations. Machine learning systems and algorithms dedicated to building destruction monitoring have to be trained with qualitative data coming from existing urban warfare theatres. The amount of available data is also critical: training deep learning architectures requires large datasets including thousands of impacted building areas over different periods of time?[10].

Conclusion

What has been described only offers a glimpse of the wide spectre of applications resulting from the use of satellite technology in support of civilian population assistance in the context of urban warfare. In the context of urban warfare, remote sensing satellites provide, as it has been seen, several advantages for the protection of civil populations. They offer a bird's-eye view of the conflict zone, which allows for better situational awareness and can help identify potential threats. Satellites can also detect changes in the environment, such as new roadblocks or movements of populations and military equipment, which can be useful in predicting and responding to attacks.

However, there are also limits to the use of remote sensing satellites in this context. For example, the resolution of the images can be limited, which makes it difficult to identify individual people or small objects. Additionally, satellite imagery is often not real-time, which means that events may have already occurred by the time the information is analyzed. Overall, while remote sensing satellites offer valuable information for protecting civilian populations, they should be used in conjunction with other sources of intelligence and information to make informed decisions.

References

[1] Z. Zhu, Y. Zhou, C. K. Seto, C. E. Stokes, C. Deng, T. A. S. Pickett and H. Tautenb?ck, “Understanding an urbanizing planet: Strategic directions for remote sensing,” Remote Sensing of Environment, vol. 228, 2019.

[2] A. Harris, “Can new technologies transform military operations in urban terrain?,” Small Wars Journal, 2003.

[3] A. Louchet, “Imagerie spatiale, géographie et renseignement,” Revue de géographie historique, vol. 8, 2016.

[4] J. Lyons, “Documenting violations of international humanitarian law from space: a critical review of geospatial analysis of satellite imagery during armed conflicts in Gaza (2009), Georgia (2008) and Sri Lanka (2009),” International review of the Red Cross, vol. 94, no. 886, 2012.

[5] D. A. Boloorani, M. Darvishi, Q. Weng and X. Liu, “Post-War Urban Damage Mapping Using InSAR: The Case of Mosul City in Iraq,” International Journal of Geo-Information, no. 10, 2021.

[6] K. Molch, “Radar Earth Observation Imagery for Urban Area Characterisation,” Joint Research Centre - Institute for the Protection and Security of the Citizen, Luxemburg, 2009.

[7] N. Durhin, “Eloigner les populations urbaines des combats et eloigner les combats des populations urbaines,” in La guerre en milieu urbain - 16ème Colloque de Bruges - 15 - 16 octobre 2015, Bruges, 2015.

[8] M. Faou, “Participation & technologies digitales (dans quelle mesure les technologies digitales contribuent-elles à la participation des populations en contexte de crise?),” Groupe URD, Plaisians, 2023.

[9] N. Bharti, X. Lu, L. Bengtsson, E. Wetter and J. A. Tatem, “Remotely measuring populations during a crisis by overlaying two data sources,” International health, vol. 7, pp. 90-98, 2015.

[10] H. Mueller, A. Groeger, J. Hersh, A. Matranga and J. Serrat, “Monitoring War Destruction from Space Using Machine Learning,” Proceedings of the National Academy Science, vol. 18, no. 23, 2023.

[11] L. A. DiMarco, Concrete Hell: Urban Warfare From Stalingrad to Iraq, Oxford: Osprey Publishing, 2012.