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Assessing the January 6, 2021 Violent Takeover of the U.S. Capitol Building: The Threat and the Security Technology Response

By Dr. Joshua Sinai, Professor of Practice of Counterterrorism Studies at Capitol Technology University

This article will assess the takeover of the U.S. Capitol Building on January 6, 2021 from the perspective of counter-terrorism, by focusing on the types of security technologies the FBI and other law enforcement authorities have been using to identify and, if possible, accumulate sufficient evidence to arrest the alleged suspects who may have been involved in the event.

During the event, just before 1:00 pm, a crowd estimated at around 800 persons (out of some 10,000 demonstrators) breached the police perimeters, broke windows, and stormed into the U.S. Capitol Building where a joint session of Congress was beginning the Electoral College vote count to formalize Democratic Party candidate Joe Biden’s victory in the November 4, 2021 presidential election1. Once inside the building, some of these individuals proceeded for several hours to occupy, vandalize, and loot congressional offices, including the Senate Chamber. At around 2:00 pm, the Capitol Police placed the building under lockdown, with the lawmakers inside quickly evacuated to safety. After several hours, the Capitol Police succeeded in clearing the rioters from the building, with some of them arrested, while many others made their way back to their homes around the country. At 6:00 pm, it was announced that the interior of the Capitol had been secured and no intruders remained in the building.

During the occupation of the Capitol building, five people died (four of the alleged participants in the takeover and a Capitol policemen), with more than 140 others wounded.

In the attack’s aftermath, as of early March, federal authorities had reportedly identified more than 540 alleged suspects and arrested 275 of them in connection with the Capitol siege2.

Counter-Terrorism Security Technologies

For the counter-terrorism community, there are numerous findings about the relatively quick manner in which the estimated 540 individuals alleged to have participated in the takeover of the Capitol building were identified and tracked. These include types of investigatory security technologies employed by law enforcement to identify and arrest the alleged participants at their various locations around the country. Alleged participants posted photos and videos of their activities outside and inside the building on various social media websites such as Twitter, Facebook, Instagram, and others, with many of them livestreaming themselves. In addition to these social media posts, videos from surveillance cameras outside and inside the Capitol building existed making it just a matter of time before these participants were identified.

Many of the alleged participants were identified relatively quickly by law enforcement authorities due to several investigatory methods. The first consisted of the public’s cooperation with the Department of Homeland Security’s motto that “if you see something, say something.” With the FBI posting a “most wanted” online portal several days after the takeover with the photos of numerous alleged participants, many of them were identified by persons who recognized them in their communities and reported their findings to the FBI and other law enforcement authorities. In other cases, in what can be termed crowdsourcing, additional identification photos were provided to the FBI by independent researchers who had tracked them on their own. It is reported that, in total, the FBI’s online portal had collected an estimated 270,000 pieces of digital media posted on social media of the alleged participants3.

In a second method, it is reported that the FBI used its access to facial recognition software tools to identify additional alleged participants and to confirm their presence in the building for prosecutorial purposes2. Facial recognition software identifies unique facial signatures on video surveillance footage to match them to databases of recognized faces, such as police mugshots of arrested individuals or their social media photos4.

In a third method, the Capitol grounds and building interiors are extensively fitted with surveillance tools, such as high-tech cameras, the footage of which has been used in the investigation.  

In a fourth method, the geo-spatial data in the Washington, DC region’s extensive Wi-Fi networks and cell towers were reportedly downloaded to capture mobile-phone data from the cellphones carried by the insurrectionists who posted their activities on social media websites. This made it possible for law enforcement to track their movements inside the building, as well as their return to their homes around the country, resulting in their arrest.  

In a fifth method, in the attack’s aftermath, the FBI was reported to be closely monitoring and arresting the militant groups’ leaders and their associates who were allegedly involved in the Capitol building’s takeover, making it more difficult for such groups to operate openly and possibly re-organize for other attacks5.

In a final method, the private sector’s social media companies, such as Twitter and Facebook, as well as website hosting companies such as Amazon and Apple, have clamped down on the spread of hatred and disinformation by the militants who engaged in the Capitol building’s takeover, including their supporters around the country, by taking down their extremist websites or removing their online accounts. Marginalizing their presence on social media sites has limited such militants’ ability to spread their extremist propaganda and mobilize their followers into violent activities.  


In the discipline of counterterrorism studies, the ability of the U.S. government’s law enforcement agencies to so quickly round up many of the alleged participants in the U.S. Capitol’s takeover is a significant metric of effectiveness. It is the objective of counterterrorism campaigns to transform one’s terrorist adversaries from “hunters” to being “hunted,” thereby eliminating their capability to initiate attacks and placing them on the defensive as they fear being arrested or having their cells and plots penetrated by informers.

One of the reasons for law enforcements’ effectiveness in identifying and rounding up many of the alleged participants is their utilization of latest investigatory security technologies, especially in scraping their postings and photos in cyberspace’s social media sites, as well as their digital phones’ geo-spatial coordinates. For these and other reasons, it is important for universities to train the next generations of technologists and engineers to develop new security technologies to counter any new communications and related technologies that might be used by terrorists in this continuously evolving “cat and mouse” game between counterterrorism agencies and the terrorists who challenge them.  

Capitol Technology University offers an online Bachelor of Science (BS) in Counterterrorism and an online Doctor of Philosophy (PhD) in Counterterrorism.

1. Demirjian, K. (2021, February 25). Capitol Police chief says extremists have discussed attack on Congress during Biden’s first joint address. Retrieved from

2. BBC News. (2021, March 5). Capitol riots: Who has the FBI arrested so far? Retrieved from

3. Rev. (2021, March 2). FBI Director Chris Wray Opening Statement Transcript: Calls Capitol Attack “Domestic Terrorism”. Retrieved from

4. Carnevale, T. (2021, January 8). U.S. Capitol Attack: IDing Domestic Terrorists Using Facial Recognition and Video Surveillance. Retrieved from

5. Marino, C. (2021, February 10). No more hiding in plain sight for domestic extremists and white supremacists. Retrieved from