The attack in New York City Tuesday afternoon highlights the growing law enforcement challenge of preventing terrorist attacks carried out not with explosives or firearms, but with vehicles.
The suspected attacker, Sayfullo Saipov, drove a truck Tuesday afternoon into pedestrians and cyclists on a lower Manhattan bike path, killing eight people. Mr. Saipov “appears to have followed almost exactly to a T the instructions that ISIS has put out on its social media channels,” said John Miller, the New York Police Department’s deputy commissioner for counterterrorism and intelligence, during a press conference Wednesday.
Late Wednesday, Mr. Saipov appeared in a courtroom in downtown Manhattan after being charged with one count of providing material support to a foreign terrorist organization and one count of violence and destruction of motor vehicles. He did not enter a plea. His lawyer, David Patton, said he would not seek bail for Mr. Saipov at this time.
The November 2016 issue of Rumiyah, an ISIS propaganda magazine, called vehicles one of the “safest and easiest weapons one could employ” to carry out a lethal attack because vehicles, unlike knives and other weapons, arouse little suspicion. Recent attacks in Barcelona; London; and Nice, France, all used similar methods and left scores dead.
“It’s a horrible situation. We have this methodology that is becoming more widespread and not a whole lot of ways to defeat it,” said Mike Sena, director of the Northern California Regional Intelligence Center, which identifies threats in the region and shares information with local law enforcement.
Law-enforcement experts say the low-cost, high-impact nature of such attacks make them hard to foresee and stave off.
Renting vehicles only takes a driver’s license and a credit card, and securing every public space where people are walking is impossible, said Mr. Sena, who is the president of the national association for fusion centers. “You can’t cordon off all the walkways, the bike lanes, the crosswalks,” he said.
Law-enforcement officials try to stop these types of attacks by encouraging rental agencies to report suspicious behavior to police, he said. False identification and documents or any overheard threats can be tipoffs.
When outdoor festivities are planned in the region, the fusion center sends out alerts to local police agencies, asking if there are any reports of stolen heavy-duty vehicles that could be used as weapons, Mr. Sena said.
Tourist destinations like Las Vegas and New Orleans have recently taken measures to protect crowded pedestrian areas prompted in part by vehicle attacks around the world.
Work has begun to install 800 steel posts between the street and sidewalks along the Las Vegas Strip where masses of people stroll between casinos. The plan was approved this summer after police officials there cited the attacks around the world as well as the danger of drunken drivers.
In New Orleans, the city has sought this year to improve safety for revelers along Bourbon Street with different types of barriers that block cars.
“They are part of a larger effort to keep New Orleans residents and visitors safe and are designed to impede attacks similar to the one that took place Tuesday in New York City,” said Gary Scheets, a New Orleans police spokesman.
On Wednesday, New York lawmakers called for the installation of traffic barriers—including bollards, which are posts about the size of fire hydrants—to keep vehicles away from bike paths and other walkways. In May, when a man plowed his car into a crowded sidewalk in Times Square and killed one woman, the car was stopped by a steel bollard in the square. The bollards appeared to have helped prevent more deaths, analysts have said.
Predicting which individuals could be preparing to rent a truck to carry out an attack is also a major challenge for law enforcement.
In New York alone, hundreds of individuals are likely on the FBI’s radar for possible terrorist activity, and many of these investigations begin with social media postings that support Islamic State or other groups, according to former law-enforcement officials.
Sharing pro-ISIS posts online is generally protected by the First Amendment. Law enforcement is often forced to monitor these postings from afar, which requires significant resources and can go on for years before the individual takes steps in real life to warrant criminal charges, said counterterrorism experts.
The time it takes for someone to switch from social media posts to actual violence can be quick.
“You have this individual who may be radicalizing by consuming content themselves, and they may not have direct orders from terrorists overseas,” said Nate Snyder, a former counterterrorism official at the Department of Homeland Security. “It’s very hard to detect if an individual gets inspired and suddenly decides to do a DIY terrorist attack.” In a recent Brooklyn case involving ISIS sympathizers from Uzbekistan, federal agents visited the home of one of the defendants in 2014 after he posted on an Uzbek-language website about his allegiance to ISIS and whether he should kill President Barack Obama as an act of martyrdom. The defendant, Abdurasul Juraboev, told the agents he wanted to harm Mr. Obama but didn’t have an imminent plan to do so. Mr. Juraboev wasn’t arrested until seven months later.
For many ISIS sympathizers, investigators may introduce an informant or undercover agent to help prompt an arrest. Last month, criminal charges were unsealed against three men who allegedly plotted bombings in New York City, including in Times Square, to support Islamic State. The case was largely built on the defendants’ communications with an undercover agent.
Some law enforcement offices have tried to intervene early on before an arrest is warranted, especially with children and teenagers who support Islamic State on social media.
As more individuals radicalize by consuming online propaganda at home, law-enforcement officials have tried to build closer connections with local communities to encourage parents, teachers and others who may be the first to notice suspicious activity. The effort has faced obstacles, partly due to uncertainty and fear about what will happen to the individual if he or she is reported to law enforcement.