As a CIA agent, Bob Baer has made car bombs. As a documentary filmmaker, he has interviewed terrorists, insurgents and members of the Mafia about why they use the weapons. Despite all that, he still doesn't know how to stop them.
"There is no defence," he said yesterday. "They're such an anonymous weapon, it just makes us extremely vulnerable."
A failed explosive left in a Nissan Pathfinder in New York City's Times Square on Saturday has forced North Americans to confront the possibility of car bombs on city streets. The improvised, mobile weapon has brought terror to the Middle East, plagued military forces in Iraq and Afghanistan and been employed by everyone from the IRA to Timothy McVeigh.
They are cheap, deadly and almost impossible to see coming. So how do you protect yourself against a weapon that involves little more than a car and a bag of fertilizer?
Mr. Baer, who was a Middle East field agent for the CIA (famously depicted by George Clooney in Syriana) and released a documentary in 2008 called Car Bomb, said fuel-based explosives cannot be detected by sniffer dogs. And while a vigilant public has learned to report unattended baggage in airports, cars can be parked almost anywhere without raising an eyebrow.
"It's low tech, just like using our planes against us," said Mr. Baer. "Now it's using our cars against us. And that's the vulnerability of our society."
The first known car bomb was actually a horse-drawn wagon, detonated in 1920 in New York's financial district, killing 38 and wounding 143. The cart was loaded with 100 pounds of dynamite and cast-iron weights, and was triggered by a timer in front of J.P. Morgan & Co. bank. Investigators attempted to trace the culprit by tracking down the blacksmith who had cared for the horse, and eventually linked the event to Mario Buda, an Italian anarchist trained in explosives.
Since then, car bombs have been used around the world, adopted by the Viet Cong, the IRA, Pablo Escobar and by fighters in Afghanistan. Timothy McVeigh parked a rental truck full of fertilizer and fuel in front of the Federal Building in Oklahoma City in 1995, and they were used in the East African embassy bombings in 1998.
Wesley Wark, an expert in national security issues, said the weapon has spread around the world with the evolution of the automobile. And there is only one common denominator shared by those who use them, he says: the desire to do maximum damage with minimal tools.
The modern age of terrorist car bombings began with the Lebanese Civil War, he said, which stretched from 1975 to 1990.
"Not only did they kill lots of Western soldiers in Beirut, but they also achieved a political objective which was to drive the United States out of Lebanon," he said. "From that moment on, it was very powerfully established that car bombs could be a weapon of mass destruction and a political tool."
Today, Mr. Wark said car bombs are the symbol of modern, urban terrorism, and can be made by anyone with bad intentions.
The technology and materials are commercially available, he said, and the Internet provides detailed instructions on how to build a bomb. But buying a bag of fertilizer at your local Home Depot, or typing "make a bomb" into Google is not necessarily going to gain the attention of police.
"You can't put security tags on the components of these things, and on the face of it that is a great boon to terrorists and a great disadvantage for law enforcement," he said.
Since 2001, counterterrorism work has gotten increasingly high-tech, monitoring communication networks and tracking the international financing of specific groups.
But building a car bomb is inexpensive and can be done alone, he said, and will not necessarily be uncovered through good intelligence.
"Law enforcement officials are obsessed with technological fixes," he said. "But I don't think there's anyway you could build a technological screening device that would alert you to the sudden presence of a truck bomb."
Certain buildings can be protected, barricading themselves in like the U.S. Embassy in Ottawa, but Mr. Wark said that simply deflects attention to more public spaces.
He believes the only effective means of stopping car bombs is to increase closed circuit surveillance, step up police presence on the streets and reach out to a network of volunteer informants, like the street vendors who alerted police to the bomb in Times Square.
In New York, Mr. Baer says disaster was averted only because the man behind the attempted bombing did not appear to know what he was doing.
"You don't want the experts in making these things anywhere near this country," he said.
He refers to car bombs as the "poor man's air force," an inexpensive, simple weapon with a high casualty rate, that can make its way almost anywhere.
"I mean, it works," he said. "And there's nothing you can do about it, anybody can be a victim."