The next attack: terrorists in Iraq are becoming proficient at blowing up oil refineries. Similar plants in a handful of American cities represent our greatest vulnerability. We could easily be making them less dangerous. But we're not.

Consider this. It's a warm Friday evening in June, and 40,000 baseball fans are gathered at Philadelphia's Cities Bank Park to watch the Phillies play the New York Mets. Most of the stadium's 21,000 parking spaces are filled. Just a few hundred yards away, Interstate 95 is crowded with weekend travelers. Two miles due west, workers on the night shift are starting to arrive at the thousand-acre Sunoco oil refinery on the banks of the Schuylkill River. A light breeze is blowing toward the east.

Across the Delaware River, three young men gather in a vacant lot. The leader of the group is a British national, a second-generation Pakistani from Liverpool who spent much of 2004 in Iraq. He has received training in bomb making from an Iranian tutor in southern Iraq and participated in attacks on Iraqi oil refineries. In the spring of 2005, a few months after returning from Iraq, the British-born jihadist traveled to the United States on a flight from London. Having never run afoul of the law in the United Kingdom, his name was not on the traveler watch list of the Transportation Security Administration (TSA). Further, as a British subject he was able to travel to New York without a visa.

With a letter of introduction from a radical British sheikh, the jihadist found his way to a Jersey City mosque. There, the local imam put him in contact with two Americans: a college student and his older cousin, both of whom had become adherents of the teachings of the radical Egyptian philosopher Sayyid Quth. The three hatched a plan to use a commercial tanker truck to target the Sunoco refinery in southern Philadelphia.

Thousands of tanker trucks operate in the tristate area of New York, New Jersey, and Connecticut. The older cousin holds a commercial driver's license and has been a truck driver for more than five years. In the summer of 2006, he provided biographical information and fingerprints to the TSA to get a hazardous materials endorsement added to his license. This allowed him to get a job driving for an independent gasoline distributor. The younger cousin obtained a job as an apprentice painter among the thousands of contractors who work on the Sunoco facility each day. His mission was to scout out the best target and the truck route to get to it.

In the late afternoon before the Phillies-Mets game, the older cousin drives his truck to the Valero Energy terminal and receives a full load of premium gasoline. Instead of making his first scheduled stop, he drives to a nearby rendezvous point to join up with his two coconspirators. The younger cousin is driving a pickup truck armed with a small fertilizer bomb. The British jihadist opens his car trunk and carefully removes two suicide vests packed with explosives. On the evening before, the two cousins had dressed in white and recorded their martyrdom videos.

Shortly after 7 p.m., as the fans at the ballpark rise to sing the national anthem, the tanker truck and pickup approach the entrance to the Sunoco facility. Abruptly, the driver of the pickup accelerates into the guard shack, detonating the explosives. The explosion knocks out the roll-away gate, allowing the larger truck to drive in. Soon, the British jihadist locates his target, a large storage tank that is well marked with hazard placards. Crying "Allah is great!" he detonates his vest. The explosion sends up a ball of flame 200 feet high, immediately killing everyone within a hundred yards of the truck. The secondary explosions kill many more employees, crippling the refinery's ability to put its emergency response plan in place.

Two miles away, fans at Citizens Bank Park go quiet when the concussive force and noise of the explosion reach them. The umpire stops the game as security officials scramble to get more information. At the refinery, the secondary explosions have ruptured pipelines to several smaller pressurized tanks that contain thousands of gallons of anhydrous hydrogen fluoride. The warm evening and the heat of the raging fires nearby cause the hydrofluoric acid to evaporate and form a concentrated, colorless vapor, which, carried by the light westerly wind, moves slowly across the interstate and toward the blue-collar neighborhood north of Roosevelt Park.

An announcement comes over the stadium's loudspeaker, saying there has been an accident at a nearby refinery. The crowd is directed to evacuate calmly and drive north, toward the center of Philadelphia. As families scramble to get to their cars, a pungent odor reaches them, and they experience a burning sensation in their noses and mouths. Gridlock sets in almost immediately. Interstate 95 is already congested with weekend travelers, and Interstate 76 has been shut down as dozens of emergency vehicles head for the refinery. Twenty thousand vehicles cannot leave the area at the same time. Thousands of people are trapped in their cars as the hydrofluoric cloud drifts over them, burning their eyes and eyelids. Soon, their lungs become inflamed and congested, depriving them of oxygen and leading to seizures. Most die within ten hours.

This is a fictional scenario, of course, but one that remains entirely plausible more than five years after the attacks of 9/11. Readers may be surprised to learn that an oil refinery can pose such a huge threat; terrorists, rest assured, are not. Al-Qaeda has been acquiring experience in these kinds of attacks in Iraq and Saudi Arabia and sharing the details of constructing improvised explosive devices in Internet chat rooms. All the information on the dangers of hydrofluoric acid and the vulnerability of the Sunoco facility can be found in publicly available reports that are accessible with the click of a mouse. And there are dozens of other similar plants near urban areas--from refineries to chemical factories to water-treatment facilities--where, to this day, in a worst-case scenario, hundreds of thousands of Americans could be killed or injured.

Much has been said about how Iraq is a training ground for terrorists, but it's rarely mentioned that the training is in precisely the sort of terrorism to which the United States is most vulnerable: attacks on our unsecured industrial facilities such as refineries and chemical plants. Between January 2004 and March 2006, insurgents carried out attacks on oil and gas pipelines that cost Iraq more than $16 billion in lost oil revenue. Successful attacks on the electrical grid have kept Iraq's average daily output at 5 to 10 percent below the prewar level, despite the $1.2 billion the United States has spent to improve the country's electrical production. Terrorists are cataloging and sharing their new skills online. And many foreign insurgents now return to their native lands with the experience of successfully targeting the kinds of complex systems that support economic and daily life within advanced societies.

Unfortunately, in the five years since 9/11, Washington has barely gone through the motions in its efforts to address the vulnerability of our chemical plants. While the Bush administration took us to war with the aim of protecting us from weapons of mass destruction produced abroad, it has shown little appetite for managing the risk of our most dangerous weapons of mass destruction at home. Over the last five years, bipartisan legislation designed to make chemical plants less appealing to terrorists has faced an uphill battle with the White House, which has resisted any legislative effort that imposes tougher security regulations on the industry. (See "Dick Cheney's Dangerous Son-in-Law," by Art Levine, p. 44.)

Democrats, having won majorities in the House and Senate, are trying to implement the recommendations of the 9/11 Commission. Unfortunately, because the commission's report says little about the issue of chemical security, this danger is still being neglected. This is both senseless and reckless. The problem of chemical security is too urgent to wait another year. It can be solved now, and it won't bankrupt the country to do it.

Not rocket science 

To understand why meaningful chemical security legislation has languished for more than five years, it helps to sit in the Bush administration's seat in the immediate aftermath of 9/11. As members of the administration surveyed the United States, they saw a country that was impossibly vulnerable to attack by terrorists who had taken them by surprise. There were thousands of miles of unsecured borders and countless easy targets: stadiums, school buses, trains, tunnels, and so forth. They concluded that it would be immensely expensive--and, ultimately, futile--to attempt to protect them all.

The administration decided that the only defense was a determined offense. This notion that it was impossible to undertake effective actions at home that would insulate us from all forms of terrorism--also meant that the White House did not need to revisit its core political views. Because 85 percent of the critical infrastructure within the United States is privately owned, federal efforts to advance homeland security would have clashed with the conservative belief that Washington should avoid regulating industry. In July 2002, the White House made this thinking official doctrine when it quietly released The National Strategy for Homeland Security. The policy paper establishes that "the government should only address those activities that the market does not adequately provide--for example, national defense and border security." However, as a rule, the government found, "sufficient incentives exist in the private market to supply protection. In these cases we should rely on the private sector." The White House strategy ended up delegating virtually the entire job of protecting the modern foundations of our lives to the companies that own and operate them. Meanwhile, the administration resisted any efforts by Democrats and a few Republican allies to change this. Oklahoma Senator James Inhofe summed up the administration's thinking when he noted in 2003 that "[l]iberals wanted to use the tragedy of Sept. 11 as an excuse to regulate more."

The White House was incorrect on all counts, however. For one thing, taking the fight to the enemy has not, at least in the near term, reduced the threat of terrorism. In fact, the most recent National Intelligence Estimate states that the risk of terrorism against the United States, has, if anything, increased in the wake of the war in Iraq. But the administration was also wrong to conclude that there are an infinite number of targets. The number of targets that matter is quite manageable.

Terrorists hoping to hit the United States operate under a very significant constraint. It turns out to be very difficult to assemble a group of Islamic terrorists inside the country. If al-Qaeda has a pool of willing and suicidal recruits in the United States, it is, at best, tiny. In fact, the case of September 11 suggests that reliable jihadists cannot easily be recruited on U.S. soil, but must instead be imported. Even then, an operative must also be capable of working here without drawing undue attention to himself, which has become more difficult since 9/11.

Typically there must be a lengthy process of intense social conditioning to "radicalize" a recruit to the point where they will become willing to sacrifice their lives. Any suicide bombers a terrorist organization has in the United States are therefore tremendously valuable. They are unlikely to be squandered on lesser targets such as shopping centers, school yards, or sports events, which, if attacked, would certainly cause short-term fear but would have little lasting impact. Small-scale suicide bombings work well in countries like Israel or Iraq, where the pool of recruits is large. In the United States, however, a suicide-bombing campaign cannot be sustained, and therefore cannot be effective as a long-term strategy.

From al-Qaeda's perspective, then, not all targets are equal. Today's terrorist masterminds know that the main benefit of attacks is that they cause mass deaths and inflict large economic costs. The most attractive attack options are those that have the potential to do the most damage for the least money. As Osama bin Laden himself claimed in a videotape broadcast on Al Jazeera on November 1, 2004, "Al-Qaeda spent $500,000 on the event, while America, in the incident and its aftermath, lost--according to the lowest estimate--more than $500 billion. Meaning that every dollar of al-Qaeda defeated a million dollars by the permission of Allah, besides the loss of a huge number of jobs."

All of this translates into two core realities about the terrorism threat which have been largely overlooked since 9/11. First, radical Islamic jihadists are probably only interested in large attacks (the stated objective of al-Qaeda leaders is for the next attack on the United States to be bigger than 9/11), in which the ratio of death and economic damage to dollars spent on the attack is high. We are not, therefore, talking about an unbounded problem. There are a finite number of meaningful targets our enemies would find worth attacking. Second, adopting measures to protect those likely targets has value.

Unbelievably, it has taken five years for the federal government to compile a prioritized list of the most likely targets in the country. Congress demanded such a list when it passed the Department of Homeland Security Act of 2002, but the new department struggled to meet this mandate. This wasn't, however, rocket science. While attacks on the electric grid, oil and gas facilities, major ports, and the food-supply system have the potential to create the greatest cascading economic effects, it is chemical facilities near urban population centers that have the potential to inflict the greatest casualties. Placing them at the top of the list of priorities is obvious.

Playing defense

Once we identify the facilities we need to protect, the process of protecting the facilities that are the most critical and potentially lethal is not as arduous as it may first appear. We can avert the frightening scenario I laid out at the beginning of this article without placing all our faith in the fight overseas. Indeed, we must acknowledge that none of our current efforts abroad would help us foil, for example, an operation that involves a radicalized British national working with two U.S. citizens who are willing to sacrifice their lives to turn a domestic industrial facility into a weapon of mass destruction. Instead of just trying to eliminate the enemy, we must also focus more on defusing his targets.

Our national endgame should not be to just shield Americans and our critical infrastructure behind twenty-first-century versions of moats and castles. Fences and security guards will always have their limits. Over time, people become complacent and security becomes routine. Through surveillance and practice runs, a determined terrorist will find a way to penetrate physical security measures.

As a launching point, it is important to analyze why a terrorist would want to attack a particular facility. In the case of the Philadelphia refinery, the most destructive element of a terrorist attack involving explosives would not be the immediate loss of life and property inside the facility. The real danger would lie in the release of hydrofluoric acid into a densely populated area. This should lead to an obvious question: Can refineries near major urban areas use a less dangerous alternative to hydrofluoric acid so as to make them less attractive targets?

Yes, as it happens. In most cases, chemical plants that threaten nearby populations can switch to less dangerous substances. This practice is known as "inherently safer technology," or IST. For example, Lawrence Wein, a professor of management science at the Stanford Business School, has determined that for a conversion cost of $20 million to $30 million per refinery, sulfuric acid could replace hydrofluoric acid in the alkylation process used to manufacture high-octane gasoline. Certainly, sulfuric acid poses dangers as well, but unlike hydrogen fluoride it does not form a dense cloud when it is released. If Sunoco were using this alternative, it would have a nasty chemical spill on its hands if terrorists attacked in the manner described above. Sunoco employees would still be killed. But the baseball game would go on without thousands of people in the stands inhaling lethal doses of a toxic gas. Today, ninety-eight refineries in the United States are already using sulfuric acid or another safer alternative (hydrofluoric acid modified with an agent that would cause most of the acid in a cloud to fall to the ground). But that still leaves fifty refineries that pose a great risk.

The price tag for making the conversion may sound steep. However, that amount represents what Americans have been spending every two to three hours on the war in Iraq, a war that has been costing U.S. taxpayers $250 million per day since the invasion in March 2003. The federal government could provide a tax break to Sunoco for investing in this change. Or Washington could be parsimonious and simply mandate the change without offering any compensation. Sunoco could still afford it. (Last year, for example, it reported profits of $974 million.) A major refinery produces about 1 billion gallons of gasoline a year. If the cost of the refinery conversion were amortized over three years, it would only raise the production cost by one cent a gallon. Even if oil companies decided to pass on the cost to drivers at the gas pump, consumers could handle this extra burden.

Terrorism aside, embracing a safer chemical has the added benefit of reducing the risk associated with ordinary industrial accidents. Nearly two decades ago, the citizens of Texas City had a narrow brush with a hydrofluoric acid disaster. On October 30, 1987, a crane at Marathon Oil's Texas City refinery dropped its load, severing two pipelines that led to the top of a storage tank of anhydrous hydrogen fluoride. The pressurized tank released more than six thousand gallons of its hazardous contents over a forty-four-hour period; the acid formed a vaporized cloud that prompted the evacuation of a fifty-block residential area adjacent to the plant. Trees were defoliated along the route the chemical traveled, and more than a thousand people ended up in hospitals for treatment of respiratory problems and skin rashes. That was merely the worst of many similar accidents. Between 1990 and 2005, the U.S. National Response Center's Emergency Response Notification System reported 400 incidents at refineries and other facilities involving hydrofluoric acid or hydrogen fluoride. Using safer chemicals would reduce any related casualties.

Similar solutions are available for a variety of industries that use chemicals. Take public water-filtration plants, which use large quantities of chlorine. Chlorine was one of the gases used as a weapon along the western front during World War I, and was lethal for anyone caught downwind. It is often transported under pressure in liquid form by tanker trucks, which must drive through city streets to reach the treatment facilities. Then it is stored in tanks adjacent to plants that may be close to residential neighborhoods, potentially placing tens of thousands of people at risk. This risk could be alleviated by replacing chlorine with sodium hypochlorite, the active ingredient in household bleach.

Or, stuff can be moved. Hydrogen fluoride released in an unpopulated desert area doesn't cause much harm, nor would a plant in such a location attract much terrorist attention. Danger comes from placing large quantities of hazardous chemicals in congested urban locations. For this reason, Houghton Chemical Corporation decided to move the contents of several large tanks that were next to a major hotel on Boston's Charles River. The tank farm stored highly flammable liquid vinyl acetate and was on a list of 121 U.S. chemical facilities that could potentially put more than a million people in jeopardy in the event of an accident, according to the Environmental Protection Agency. After 9/11, Houghton executives decided that the risk of a miles-long toxic cloud over the Boston skyline was not something they wanted to live with, so they quietly moved the vinyl acetate to another location.

Unfortunately, most companies have not followed Houghton's admirable lead. Without a strong mandate from the federal government, it's unrealistic to think they ever will. Yet voluntary compliance is the premise of the legislation Congress passed last fall; the new rules rest on the assumption that companies will now suddenly begin taking steps they have so far refused to contemplate.

Although much is unknown about the nature of the terrorist threat, some facts are indisputable. One is that the United States will be attacked again. Another is that the next attack will result in foreseeable consequences that will cause unnecessary loss of life and destruction of property. Finally, after the next attack, the legitimate outrage that Americans will feel when they discover how little was done to address our most serious domestic vulnerabilities will provoke seismic political fallout. In the end, national resilience must complement national security as the means to meet the hazards that the twenty-first century portends. As any good boxer knows, there is strength not only in being able to deliver a punch, but also in being able to take a punch. Indeed, in the face of the catastrophic terrorist threat, the best defense may just well be a good defense.