News Advisory: Bombs are Terrorists’ Weapon of Choice

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November 16, 2023
San José, CA

Bombs have been terrorists’ choice of weapon in more than half of the attacks on public surface transportation around the world since 2004. They have also caused more than 60% of the resulting fatalities and more than three quarters of the injuries.In the third of a series of studies on the frequency and lethality of such attacks between January 2004 and December 2021, the Mineta Transportation Institute’s latest report, The Use of Explosive Devices in Attacks on Public Surface Transportation: Trends in Frequency, Lethality, and Prevention, examines the way bombs were used in 3,836 attacks on passenger train and train stations, buses, bus stations and stops, passenger ferries and terminals, rail infrastructure and operating and security staff. The attackers almost always used bombs alone, but sometimes also in combination with other weapons, such as firearms. 

The attacks killed 7,412 people and injured 21,847, an average of 1.9 fatalities and 5.7 injuries per attack. Notably, bombs are also more likely to be used in attacks in developing countries than in more economically advanced countries. 

Author Brian Jenkins, says, “While the percentage of bomb attacks globally has decreased, we found that lethality has increased, particularly in economically advanced countries, where suicide bombings are the most lethal bomb attacks. Most frequently, bombs were placed inside bus or train compartments, on railway tracks or inside train stations. The bombs in stations and compartments resulted in the most casualties. 

“However, the majority of attacks in economically advanced countries are unsuccessful, with devices discovered, malfunctioning or failing to detonate. Despite the decrease in attacks, bombs do remain very lethal—particularly in confined spaces,” he adds.

The report shows that bombers had greater success in the other countries, with vehicle-borne explosive devices (VBIEDs) being the most lethal in developing countries, followed by suicide attackers carrying bombs. 

Co-author Bruce Butterworth says this may be because explosives are easier to acquire in less developed countries or detection and prevention by authorities are weaker. “Worldwide, successful bombings have declined. More bombs are being detected before detonation, particularly in the advanced countries, although the identity of most of the individuals who have found bombs and stopped attacks is unknown. Of those who foiled attacks in those countries and whose identities are known, 40% were passengers, citizens, or employees, while the percentage in the less-developed countries was only 21%. The proportions in the two country groups were reversed for security, police, and military officials,” explains Butterworth. 

Worldwide, bombs placed in railway tracks are not very lethal, as they are usually intended to cause disruption. 

“Bombs have figured prominently in the history of political violence. Technological advances in explosives such as timing devices and remote detonation have made bombings easier and, as our findings show, have clearly become the terrorists’ weapon of choice in recent decades. 

“Restricting access to more stable and reliable explosives, alongside better intelligence and aggressive security does seem to result in less lethality from terrorist activity,” concludes Jenkins.

The Use of Explosive Devices in Attacks on Public Surface Transportation: Trends in Frequency, Lethality, and Prevention can be downloaded here.

The authors’ companion reports: 

Evolving Patterns of Violence in Developing Countries can be downloaded here.

Changing Patterns of Violence Pose New Challenges to Public Surface Transportation in the United States can be read here.



For Editors: Both key authors are available for interviews and comment on terror attacks against public transportation – please contact Bruce Butterworth at + 1 (301) 767-6853.



At the Mineta Transportation Institute (MTI) at San Jose State University (SJSU) our mission is to increase mobility for all by improving the safety, efficiency, accessibility, and convenience of our nations’ transportation system. Through research, education, workforce development and technology transfer, we help create a connected world. Founded in 1991, MTI is a university transportation center funded by the US Department of Transportation, the California Department of Transportation, and public and private grants, including those made available by the Road Repair and Accountability Act of 2017 (SB1). MTI is affiliated with SJSU’s Lucas College and Graduate School of Business.

Brian Michael Jenkins is the Director of the Mineta Transportation Institute’s Allied Telesis National Transportation Security Center and since 1997 has directed the Institute’s continuing research on protecting surface transportation against terrorism and other serious forms of crime. Bruce R. Butterworth is a Senior Transportation Security Researcher at MTI and former Director of Aviation Security Operations at the Federal Aviation Administration. Bruce has taken a leading role in creating MTI’s unique database of attacks on public surface transportation. Sachi Yagyu contributed to this report. She is a Transportation Security Specialist at MTI, and previously served as a Research Librarian and Library Research Services Team Lead at the RAND Corporation. She holds an MLS Degree from UCLA.

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