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Q&A with Dr. Joshua Sinai on the terroristic threat of vehicular ramming

Recently, Cap Tech's own Dr. Joshua Sinai published an article for The Journal of Counterterrorism & Homeland Security International titled "The Threat of Terrorist Vehicular Ramming Attacks and Prevention Measures." To read the published article, click here

Dr. Sinai graciously agreed to a Question and Answer session to summarize his writing and shed more light on this national security threat.

Q: Could you summarize what your article discusses?

A: Firearms, improvised explosive devices (IEDs) and knives have long been the weapons of choice for terrorists, but in latest warfare tactics, motor vehicles are being weaponized as their instrument for ramming attacks against pedestrians on sidewalks and public crowds on streets. In this tactic, trucks, vans or cars are intentionally driven into public crowds, sometimes over long stretches of road before the attacks are terminated, usually through crashes. In some of the incidents, the attackers’ violence continues when they flee their stopped vehicles and use knives to inflict further damage on the nearby pedestrians.

To examine these issues, the article defines this type of vehicle ramming attack (VRA), provides a chronological listing of a representative sample of 20 incidents along the period of 2004 to 2021, assesses three types of VRAs, their ideological motivation, the tactics, techniques and procedures (TTPs) used in the attacks, and explains the reasons for the recent frequency in the incidents of such attacks.

Attesting to the frequency of such incidents, after the article was submitted for publication in early March 2021, a month later, on April 3, an attacker deliberately rammed his vehicle against U.S. Capitol Police officers, killing one of them and wounding another. After the assailant got out of his stalled car, he was shot dead by the responding police officers after he used a knife to attempt to further kill his targets. His motivation for the attack is still under investigation.


Q: Why do terrorists employ the tactic of vehicular ramming in their attacks?

A: The motivation for conducting vehicular ramming attacks is similar to what drives terrorists in general: using any means of violence to kill people, damage property, and cause panic, anxiety and psychological damage on their targeted adversaries as a way to publicize their cause and coerce governments to give in to their demands.

Vehicles serve as a “weapon of choice” for terrorists because, unlike firearms and explosives, they are easily acquirable, whether as their own vehicles, as rentals, or through theft. Unlike guns and bomb explosives, vehicles do not arouse suspicion as potential signs of an attack by an imminent perpetrator.

Vehicles also enable the perpetrators to become “smart attackers” because they can easily make their way to their targets as they are seen as normal means of transportation, yet can unexpectedly change direction, if needed, from empty to crowded streets, to inflict maximum lethality against crowded areas in their attacks.

Finally, using vehicles enables attackers to exploit the soft target nature of public places where pedestrians and crowds are generally undefended by any barriers that could prevent them from being attacked by moving vehicles.


Q: Why did you want to focus on this tactic and weapon in terrorism?

A: Terrorism is about conducting violent attacks, so it is important to understand all the tactics and weapons that terrorists use to conduct their attacks for a full picture of the threat. With the tactics of using firearms and explosives the most frequently used by terrorists, it is important to be aware of other tactics, such as vehicular ramming, that may be used less frequently and be less “warrior-like” in their approximation of military attacks, yet can be equally deadly as mass casualty weapons against their adversaries.


Q: Can you compare counterterrorism efforts for vehicular ramming to efforts to more common methods of attack such as shootings or bombings? What unique challenges and complexities do you face in trying to prevent vehicular attacks?

A: There are actually some similarities in countering these types of terrorist threats. The Department of Homeland Security’s defensive protocol of “run, hide, and fight” to evade violent shooters can also be used by potential victims to evade oncoming vehicle ramming attacks, if possible, with various means used to “fight” back at the driver, including when he attempts to leave the stopped vehicle. Also, during the pre-incident phases, like potential violent shooters, it is possible for those contemplating using vehicles in their attacks to leak their violent intentions in online posts, so, if observed by others, these can be reported to the appropriate authorities for preemptive prevention.

Some of the unique challenges in preventing vehicular attacks include conducting a risk assessment to prioritize where defensive measures need to be implemented in the areas where such attacks can take place. For example, where should concrete barriers, such as bollards, be placed to keep vehicles from driving up onto pedestrian sidewalks. This is crucial at special events that are held outdoors.


Q: Can you explain how the pre-incident trajectory you use can be applied to vehicular ramming attacks? How is it possible to potentially identify terrorists before they commit a vehicular ramming?

A: Interestingly, the pre-incident trajectory into violence by perpetrators who conduct shooting and bombing attacks is similar to those who carry out vehicle ramming attacks. They all progress through an attack’s pre-incident triggering, planning, preparation, targeting, and executing (TPPTE) phases, with each of these phases providing intervention points for those associated with such individuals to identify suspicious mindsets and behaviors that might indicate an intention to carry out a terrorist attack. In the event such individuals choose to employ a vehicle to carry out their attack, suspicious early warning indicators might be unusual preoccupation with how a vehicle might be driven to attack crowds on a sidewalk or public event, how to overcome street barriers, or online research on imminent street events, such as street protests by their adversary political rivals. As mentioned earlier, employees at vehicle rental agencies need to be informed of suspicious indicators that point to how persons who intend to drive their rental cars for malevolent purposes behave at the time of the rental request.


Q: What specialized technology, if any, exists to tackle this specific kind of attack?

A: Although the article briefly discusses this important issue, with bollards and other barriers in public spaces used to prevent or ameliorate such attacks, there are several new technologies that are being proposed to stop such moving vehicles. With heavy trucks used in some of the ramming attacks as stolen vehicles, one new technology is the installation of an automatic emergency braking system (AEBS) to detect the possibility of a collision that would automatically apply the vehicle’s brakes.1 

It is also possible, however, for terrorists to hack into a moving vehicle’s extensive electronics system to steer it off course to ram into crowds, so anti-hacking mechanisms need to be upgraded to prevent electronic systems in vehicles from being hacked.


Q: What improvements do you feel need to be made to current counterterrorism efforts in order to have fewer of these attacks?

A: Implementing physical protective measures needs to be accompanied by a public awareness campaign. At the individual level, this should include raising public awareness of the pre-incident suspicious indicators that potential vehicular attackers might exhibit and the appropriate authorities to report such suspicions, whether mental health counselor or law enforcement agencies. At the public level, law enforcement and transportation authorities need to promote public awareness of suspicious driving patterns by an incoming vehicle that might indicate that an attack might be underway against pedestrians and crowds.

In a second measure, like the background checks by gun store salesmen that are supposed to prevent the purchase of firearms by ineligible individuals, a reporting guideline and procedure protocol needs to be established for employees at vehicle rental companies to report suspicious activities by customers with a potential terrorist intent, particularly when such individuals seek to rent vehicles that appear to be outside their normal transportation needs.


Q: What trends have you noticed in relation to this type of attack? Are there any political, economic or social occurrences that tend to trigger a spike in this kind of violence, or does it tend to be largely random or unrelated to current social climate?

A: The current highly polarized political environment, with disaffected individuals of all political positions, joining mass street protests against what they perceive to be political and social injustices that need to be fixed, is one of the motivators for some militants to use their vehicles to ram into their adversary street protestors, especially when a police presence might make it difficult for them to use firearms or explosives to reach their targets.


Q: What is your process for writing an article to be published in a journal?

A: To write an article, one should come up with an interesting topic and a unique way of covering it.

It is also important to decide if the article will be published in an academic or general interest journal.

For an academic journal in the social sciences, it is necessary to formulate a central hypothesis to be tested and validated through a qualitative or quantitative methodology, with the evidence backed up by sources. The length of such articles is usually 5,000 words or longer.

For a more “popular” journal, such as “The Journal of Counterterrorism & Homeland Security International,” where my article was published, that is read by public safety practitioners, the writing style is more journalistic and the articles are shorter in length.

Ideally, whether an article is published in an academic or “popular” journal it will cover the subject in a way that the readers will be able to use its approach to upgrade their daily work.



1. Lawrence, C. (2017, September 1). Can technology stop terrorist vehicle ramming attacks? ReadWrite.

2. Sinai, J. (2021, April). The Threat of Terrorist Vehicular Ramming Attacks and Prevention Measures The Journal of Counterterrorism & Homeland Security International, Volume 26, No. 3


Dr. Joshua Sinai is a Professor of Practice, Counterterrorism Studies, at Capitol Technology University. His more than 30-year career in Washington, DC, has included working as a contractor at the Department of Homeland Security’s National Operations Center (when it was first stood up) and DHS’s Science & Technology Directorate, as well as at the FBI’s Foreign Terrorist Tracking Force (FTTTF) and the Federal Protective Service’s (FPS) Training Branch. He also serves as Book Reviews Editor of the online bi-monthly academic journal “Perspectives on Terrorism,” for which he writes the “Counterterrorism Bookshelf” review column.