The images are disturbing: cargo trucks plowing into crowds of people enjoying holiday street festivals and markets.
In recent years, these terrorist attacks have happened often — mostly in European countries — leaving dozens of people dead and hundreds injured.
Now, the U.S. Transportation Security Administration wants truck rental agencies to be more vigilant in efforts to prevent these attacks, releasing a report this week that outlines the increased threat of such incidents.
The report, titled "Vehicle ramming attacks: Threat landscape, indicators and countermeasures," notes that in the last three years, at least 173 people have been killed and more than 700 wounded in 17 ramming attacks around the world. Within the six-page report, the TSA urges truck companies to report suspicious activity — for example, would-be renters asking about altering a truck — to law enforcement officials. Moreover, the report warns that no community, "large or small, rural or urban, is immune to attacks of this kind by organized or 'lone wolf'" attackers.
"Terrorist organizations overseas have advocated conducting vehicle ramming attacks — using modified or unmodified motor vehicles — against crowds, buildings and other vehicles," the TSA writes in the report. "Such attacks could target locations where large numbers of people congregate, including parades and other celebratory gatherings, sporting events, entertainment venues or shopping centers."
Indeed, leaders of the Islamic State have encouraged followers to carry out truck ramming attacks. Abu Mohammed Adnani, a former spokesman for the Islamic State who was killed in a U.S. airstrike in Syria last year, had encouraged followers in a September 2014 statement to use whatever weapons necessary, including vehicles, in terrorist attacks.
In December, a Tunisian man with ties to the Islamic State deliberately drove a 27-ton truck into a Christmas market in Berlin, killing 12 people and wounding 56 others. And in July, as thousands crammed into the streets of Nice, France, for Bastille Day celebrations, another man, influenced by the Islamic State, drove a 19-ton cargo truck into a crowd, leaving 86 dead and 434 injured. Since 2014, four other truck ramming attacks have taken place in France.
Although just four of the 17 ramming attacks highlighted in the report were carried out using commercial trucks, the TSA says these vehicles, which can weigh several tons, are effective tools in such assaults.
"Commercial vehicles — distinguished by their large size, weight and carrying capacity — present an especially attractive mechanism for vehicle ramming attacks because of the ease with which they can penetrate security barriers and the large-scale damage they can inflict on people and infrastructure," notes the report.
Jake Jacoby, president of the Truck Renting and Leasing Assn., a nonprofit national trade group, said that for years his organization has worked closely with local and federal law enforcement agencies to prevent such attacks.
"This is a real threat that we take seriously," Jacoby said on Friday. "We're the front line of defense in prevention."
Randolph P. Ryerson, communications director for Penske Truck Leasing based in Reading, Pa., said his company is taking necessary precautions to stave off an attack.
In a statement, Ryerson said Penske requires two forms of valid identification to rent and that customers are screened using a watch list through a private contractor hired by the company. He said that in recent months Penske officials have met with FBI agents to learn more about potential truck ramming attacks.
Other truck rental agencies, such as U-Haul, declined to comment Friday on the precautions they take to prevent such attacks.
Truck ramming attacks have been rare in the United States, although the TSA report does highlight an incident on the campus of Ohio State University last November.
In the attack, Abdul Razak Ali Artan drove his Honda Civic onto a campus courtyard, striking several pedestrians. He then jumped out of the car with a butcher knife and began attacking people. In all, 11 were injured before Artan was shot and killed by police.
Jacoby noted that it's difficult to prevent lone wolf attacks, but that truck agencies have received insights from federal and local law enforcement.
"We always tell companies — just be aware, be aware," Jacoby said. "It's critical to be aware of who you're renting to."