Urban terrorism is not new, or even the ‘new normal’. Previous waves of terrorist activity, such as decades-long campaigns by the Irish Republican Army (IRA) in London and Euskadi Ta Askatasuna (ETA) in Madrid, consistently targeted capital cities. The most lethal terrorist attacks in history on 11 September 2001 symbolically targeted the financial and political centres of the US. Baghdad, Cairo, Islamabad, Mumbai, Buenos Aires, Beirut, Jerusalem, Paris, Jakarta, Los Angeles, Nairobi: regrettably few major urban areas are unfamiliar with major terrorist attacks.

Terrorist groups target cities because they are centres of political power and population. (Also, leftist terrorism associated with agrarian peasant insurgencies has largely subsided outside of South Asia.) In cities, more people are directly or indirectly exposed to individual terrorist acts, and the concentration of interest ensures publicity and attention. Urban systems such as mass transit also rapidly transmit the disruptive effects of terrorism citywide. Put another way, population density and urban complexity multiply the desired physical, psychological and strategic impacts of terrorism. The attractiveness of cities to terrorists will only increase: since 2007, more people live in urban than rural areas for the first time in human history; by 2050, the estimate is that 75% of global population will be urban.

The speed of urbanisation over the last few decades, especially in emerging and developing countries, has also shaped the threat environment. Rapid, often unplanned city growth leaves glaring gaps in public service provision, including law enforcement. Concurrently, the resulting close proximity of disparate ethnic, religious, linguistic and economic groups has been seen in some instances to result in social divisions. Terrorist groups strive to take advantage of gaps – for example, by cultivating safe havens and staging grounds in the anonymous urban sprawl – and exploit social divisions to radicalise sympathisers.

Threat environment

Urban terrorism is certainly evolving. Post-9/11 obstacles to al-Qaida’s preferred strategy of symbolic ‘spectacular’ attacks in top tier Western cities devolved much responsibility to homegrown, lone wolf extremists by the late 2000s. Al-Qaida propagandists have long incited sympathisers to strike local, familiar targets using any available means.  As a result, the terrorism threat environment became less severe, but also much less predictable: plots and attacks spread to secondary cities like Exeter (UK), Little Rock, Springfield, and Portland (all US), Toulouse and Nantes (France), and Victoria (Canada).

In Western countries, increased surveillance and strict controls on explosives also shifted tactics away from complex, large-scale vehicle bomb attacks against hard targets towards so-called marauding terrorist firearm attacks (MTFAs) in public spaces. Both al-Qaida- and Islamic State (IS)-affiliated terrorist groups embrace the tactic: firearms are cheap and widely available, and uncertainty around the movements, size and capabilities of mobile teams of gunmen can effectively paralyse a city during an attack. Indeed, disrupting the normal life of a city – and by extension a society – by forcing an indefinite security lockdown is likely to be part of the point of such attacks.

Urban attacks are often even more effective in emerging and developing countries, where law enforcement capabilities are usually under-developed and under-resourced. Most Western and some developing country civilian law enforcement agencies responded to earlier waves of terrorism (or social unrest) by developing units specialising in intelligence collection, hostage rescue, and building assault. Similar capabilities in most emerging and developing country police forces are non-existent or very limited, forcing them to rely on slower and blunter military intervention. The September 2013 assault on Nairobi’s Westgate shopping mall highlighted gaps – widespread globally – between the terrorist and security force capabilities.


Cities continue to develop ways to deter, prevent and mitigate terrorist attacks. The City of London instituted its famous ‘ring of steel’, the US Department of Homeland Security (DHS) disbursed risk-adjusted urban security funding after 9/11, and companies worldwide incorporated building design features and security procedures intended to thwart common attack scenarios. Many of these innovations are now standard urban planning practice, especially in the construction sector, and threat mitigation is becoming more effective and less obtrusive. In developing countries that have not responded effectively to terrorist threats either from a law enforcement or an urban planning perspective, new urbanisation projects can greatly increase localised resilience to terror attacks by adopting a threat-led approach from the feasibility stage that extends throughout the life-cycle of the project.

Recent efforts, in both the public and private sectors, revolve around ‘big data’ analysis of social media and other communications activity. The unpredictability inherent in soft target attacks – and the potential lethality of firearm assaults – puts a premium on threat identification and early warning. Many major attacks since 2014 have been cases of failing to connect intelligence dots, rather than failing to develop intelligence in the first place.

Law enforcement agencies are also working to overcome jurisdictional and organisational structures that inhibit rapid response. So-called ‘fusion centres’, which cut across agency, jurisdictional and political boundaries, are a primary response: such structures became widespread in the US after 9/11, and are currently under development in Europe. Western countries are deeply involved in supporting such structures internationally, particularly in sub-Saharan Africa.


The future is undeniably urban. This ensures that cities will also dominate the future terrorism threat environment. While cities are inherently – and impressively – resilient, even in the face of devastating attacks, they are also complex and vulnerable to disruption. The challenge for cities – meaning municipal officials, developers, planners, law enforcement, private organisations and urban residents – is to continue to innovate ways of enhancing response and resilience in tune with the changing terrorism threat environment. In particular, the rising threat to public, open access spaces is likely to encourage increased emphasis on automated threat identification and early warning/horizon scanning, as well as increased investment in more robust response capability.


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