That was far from Aum’s only failure. The cult’s first known bioterror attack involved the spraying of botulinum toxin—the extremely deadly substance that causes botulism—from three trucks at targets that included American naval bases, an airport, Japan’s parliament, and the Imperial Palace. No one got sick. No one even knew there had been attacks—the truth was discovered three years later. Another botulinum attack failed in June 1993. The same month, the cult’s first anthrax attack failed. In all, Aum made nine attempts to inflict mass death with two of the most feared bio-terrorism weapons. They killed no one. It seems that not even Aum, with all its resources, could overcome the many practical barriers to isolating virulent forms of the deadly pathogens and disseminating them broadly.
So the cult switched its focus to chemical weapons and nerve agents. Here, Aum met with considerable success, producing substantial quantities of mustard gas, sodium cyanide, VX, and sarin—the latter two being among the deadliest nerve gases. When police finally raided Aum’s facilities in 1995, the cult had enough sarin to kill an estimated 4.2 million people.
As terrifying as that is, it’s also strangely reassuring. After all, here was a cult that wanted to kill millions and it had cleared the many barriers between it and possession of weapons that were at least theoretically capable of doing just that. And yet, Aum still failed to cause mass death.
On June 27, 1994, Aum members drove a converted refrigerator truck into a residential neighborhood of Matsumoto, Japan. Inside, terrorists activated a computer-controlled system that heated liquid sarin to a vapor and blew it into the air with a fan. The wind conditions were perfect, slowly nudging the deadly cloud toward windows left open to the warm night air. Seven people died, and more than 140 suffered serious injuries.
On March 20, 1995, Aum tried another delivery method. Five members dressed in business suits and carrying umbrellas stepped aboard five different trains in the heart of Tokyo’s notoriously crowded subway system. In all, they carried eleven plastic bags filled with sarin. Placing the bags on the floor, the terrorists poked holes in them with their umbrellas and fled the trains. Three of the eleven bags failed to rupture. The other eight spilled roughly 159 ounces of sarin. As the liquid fanned out, it evaporated and vapors rose. Twelve people died. Five more were critically injured but survived. Another thirty-seven were deemed severely injured, while 984 suffered modest symptoms.
Japanese authorities raided Aum properties all over the country and were astonished at what they discovered. Despite the scale of Aum’s murderous operations, despite the cult’s many efforts to acquire the means of slaughter, despite the repeated attacks, the police had little idea what was happening in their midst. It’s hard to imagine a worse scenario: A fanatical cult with a burning desire to inflict mass slaughter has heaps of money, international connections, excellent equipment and laboratories, scientists trained at top-flight universities, and years of near-total freedom to pursue its operations. And yet Aum’s seventeen attacks with chemical or biological weapons took far fewer lives than the 168 people who died in Oklahoma City when Timothy McVeigh detonated a single bomb made of fertilizer and motor-racing fuel.
“Aum’s experience suggests—however counter-intuitively or contrary to popular belief—the significant technological difficulties faced by any non-state entity in attempting to weaponize and disseminate chemical and biological weapons effectively,” concluded the Gilmore Committee. Crucial to this failure, the committee noted, is the atmosphere within a conspiracy fueled by religious mania. “Aum scientists, socially and physically isolated and ruled by an increasingly paranoid leader, became divorced from reality and unable to make sound judgment.”
For terrorists with dreams of apocalypse, this is discouraging. Al-Qaeda and other Islamist terrorists have few of the advantages Aum had. They do not have the money, infrastructure, or equipment, or the freedom from scrutiny, or the ability to travel openly. Most important, they do not have the scientists—al-Qaeda has tried to recruit trained minds but consistently failed, which is the main reason they have never shown even a fraction of the technical sophistication of Aum. The one factor they share with the Japanese cult is the hothouse atmosphere that crippled Aum’s efforts.
As the Aum experience showed, mass-casualty terrorist attacks using chemical or biological weapons are certainly possible, but terrorists quickly discover many serious obstacles if they start down this path. There’s a reason that even the most sophisticated and ruthless terrorists have stuck almost exclusively to bombs and bullets—or, in the case of the worst terrorist attack in history, box cutters and airplane tickets.
Of course, the calculations change when weapons go nuclear. “Perhaps the only certain way for terrorists to achieve bona fide mass destruction would be to use a nuclear weapon,” wrote the Gilmore Committee. A nuclear attack would undoubtedly be an almost unimaginable horror and the contemplation of that horror inevitably stirs emotions strong enough to drive out any thought of probabilities. And that’s a mistake. Probability is always important in dealing with risks, even catastrophic risks—especially catastrophic risks. The biggest risk humanity faces is, after all, not nuclear terrorism. It is a collision with an asteroid or comet of planet-killing size. If we considered only the potential destruction of such an event and ignored its probability, we would pour trillions of dollars into the construction of vast, impenetrable, globe-girdling defense systems. But pretty much every-body—including the astronomers who wish we would spend just a little more money to detect asteroids—would say that’s a foolish waste of resources because the probability of mass extinction by collision is incredibly tiny and that money could do a lot more good down here on Earth. We shouldn’t ignore the threat—refusing to pay a modest amount of money to detect major asteroids and calculate pending collisions is ridiculous—but we also shouldn’t go crazy about it. The same cool head has to be brought to bear on nuclear terrorism.
What is the probability of an American city going up in a mushroom cloud? It’s not possible to calculate that in the way that we calculate, say, the chance that a child sitting in a properly installed car seat may die in a crash because it has never happened so there are no numbers to crunch. In the absence of data, all we can do is look at the complex facts about the construction and availability of nuclear weapons and make a judgment call.
The Gilmore Committee did that. It started by noting that the collapse of the Soviet Union did not result in Soviet nukes popping up in black markets, despite widespread fears during the 1990s. In particular, reports that Russia’s notorious “suitcase nukes” went missing did not hold up and, in any event, the devices require regular maintenance in order to function properly. Even if some disgruntled Russian officer did manage to sell a bomb, the buyers would still have the difficult job of smuggling and detonating it—the latter being particularly difficult because nuclear devices typically have tamper-proof seals and other security measures designed to prevent precisely this scenario.
As for DIY, it’s not something that can be done in the average suburban garage. “Building a nuclear device capable of producing mass destruction presents Herculean challenges for terrorists and indeed even for states with well-funded and sophisticated programs,” the Gilmore Committee wrote. In the 1980s, Saddam Hussein poured Iraq’s vast oil-funded resources into a nuclear program but failed to produce even a single weapon before the first Gulf War, and subsequent sanctions scuttled his ambitions. Apartheid South Africa did succeed in building a small nuclear arsenal, but “it took scientists and engineers—who were endowed with a large and sophisticated infrastructure—four years to build their first gun-type system (the crudest form of nuclear bomb).”