On an average day in the Port of New York and New Jersey, about 4,000 shipping containers—lined end to end, they would stretch 15 miles—are lifted off freighters and released into the arteries of American commerce. One recent morning, a U.S. Customs inspector named Michael Hegler, 47, cast a wary eye on just a fraction of that unending stream. Standing in the wheelhouse of an 850-foot Saudi Arabian ship docked at a Brooklyn terminal, taking in a view of the Statue of Liberty and a striking patch of Manhattan real estate once dominated by the World Trade Center towers, Hegler gazed down at the ship’s deck, five stories below.

It was covered with rectangular steel containers, most of them 40 feet long and stamped “NSCSA,” for the National Shipping Company of Saudi Arabia. Stacked four high and lashed to the deck with long metal rods, the containers had passed through a few exotic locales: Karachi, Pakistan; Dubai, United Arab Emirates; and Jidda, Saudi Arabia. Those ports are likely to attract the interest of American law enforcement nowadays, and Hegler was giving his full attention to the 148 containers being picked off the deck by a giant blue crane and deposited on the wharf. Normally, the men and women of U.S. Customs and Border Protection target for inspection only about 3 percent of the seven million containers that pour into the United States each year. But given the pedigree of these boxes, they would all be screened.

Tractor-trailers carried the containers 150 yards to a gamma-ray machine, a truck-mounted device that uses gamma rays instead of X-rays to penetrate an object and visualize its contents. The machine’s arm reaches over a container’s top. In the truck’s cabin, one customs inspector glanced at an electronic manifest of the container’s contents while another watched a computer screen showing the gamma-ray scans. To the uninitiated, the image looked like a dusky blur, but soon you could see the outlines of the goods—ceramic tiles, furniture, machinery, electronics, cartons of clothing. Then, something caught the inspector’s eye: inside a load of quilts from Pakistan was a long, tube-shaped metal object. Explosives? Uranium? Stinger missiles? An inspector had the container driven to a nearby warehouse for a closer look. There, inspectors unpacked the metal tubes and found . . . tractor parts. They were not listed on the manifest and thus imported illegally, but all the same they were only farm machinery. Meanwhile, Hegler and co-workers had become suspicious of several containers still on the ship and bound for other U.S. ports. Most bore small, metal and plastic shipping seals that were affixed improperly or showed signs of tampering. Hegler, who has a powerful build and curly blond hair that falls to his collar, snipped one of the seals with bolt cutters. Other inspectors swung the container doors open and slit a few boxes. They climbed over cardboard cartons to look into the container’s farthest corners. But they discovered only household goods and cases of Italian wine.

By the end of the day, Hegler and his fellow customs inspectors had found no terrorists, no weapons, nothing that could remotely be linked to Al Qaeda. The same was true that day of their counterparts at the five other port terminals in New York City and northern New Jersey, and of the thousands of customs inspectors in Charleston, Baltimore, New Orleans, Los Angeles, Oakland, Seattle and points in between. In fact, since September 11, 2001, the small army of inspectors at America’s 361 seaports, having scanned or inspected tens of thousands of containers and pored over hundreds of thousands of manifests, have found not a shred of physical evidence that smacks of a terrorist plot.

Optimists might take heart, pointing out that despite seemingly impossible odds—analysts have compared finding a weapon of mass destruction among seven million containers to catching a minnow going over Niagara Falls—the customs bureau has erected sufficient barriers to deter Al Qaeda. But pessimists have reason to fret. Customs inspectors may have simply missed a smuggled bomb or batch of missiles. If so, it’s not for lack of motivation. “Many people here watched the 9/11 attack from their office windows, and you don’t have to tell us twice what the mission is,” said Kevin McCabe, chief inspector for U.S. Customs and Border Protection at the Port of New York City and New Jersey. “It’s very clear.”

The problem is that McCabe and his co-workers are at the receiving end of a giant global conveyor belt that carries steel boxes whose contents are declared by the shipper but are rarely verified along the way. “The system is absolutely wide open, and anybody with 3,000 bucks in Asia and a little less in Europe can get a box delivered to their lot or home and they can load it to the gills with whatever they want, close it with a 50-cent lead seal, and it’s off to the races,” says Stephen E. Flynn, a 43-year-old retired Coast Guard commander and an expert on seaport security. “As I look at the cargo transport system today, when I wake up each morning and see that we haven’t had an attack, I just declare ourselves lucky. The secretary of the treasury, the secretary of defense, the secretary of commerce, the secretary of state and the president of the United States should be tossing and turning at night knowing that this system has so little security.”

The challenge of safeguarding ports and monitoring the contents of all those 20- and 40-foot boxes is daunting enough. But it also poses a quandary, pitting our need for security against the ideal of an open society and free trade. The container network is the circulatory system of the new global economy, carrying 90 percent of international commerce. Some 11 million containers are shuttled around the world, bringing $500 billion worth of goods in and out of the United States from 178,000 foreign businesses.

This system, however, was designed for speed and efficiency, not security. Following the September 11, 2001, attacks, U.S. Customs and Border Protection—now part of the Department of Homeland Security—tightened its screening of incoming containers, overhauling computer programs to target high-risk shipments and using new X-ray and gamma-ray machines to inspect them. But according to Flynn and other security experts, the government has not done nearly enough to monitor what’s being stuffed into the containers overseas. (The Department of Homeland Security did not respond to requests for comment.)

The reason for the experts’ concern is that shipping containers could readily transport chemical or biological weapons, explosives, missiles or components for nuclear weapons. Broken into small batches, such weapons could be hidden among shipments of machinery, foodstuffs or thousands of other commodities that arrive each day at American ports. Even if a container is pulled out of the trade stream and targeted for inspection by gamma-ray machines and radiation detectors, it’s possible that customs inspectors won’t spot a weapon. Twice in the past two years, ABC News has succeeded in smuggling a 15-pound lump of depleted uranium—supplied by the National Resources Defense Council, an environmental group—into U.S. ports. In both instances, inspectors ran the containers through gamma-ray and radiation screeners, but failed to detect the material. Customs officials deny the implication that the inspections system failed; they say depleted uranium is not considered dangerous and they would have spotted the sort of enriched uranium used in nuclear weapons because it emits detectable levels of radiation. But some nuclear scientists disagree, saying that, given the detection devices in use today and the radiation shielding that terrorists might employ, weapons-grade radioactive material would have been even harder to spot than the depleted uranium.

Security experts are concerned not only about the detonation of a weapon of mass destruction in a city but also about an attack on a major port. Such an assault would almost certainly force the government to shut down the nation’s container system for a significant period of time, crippling major sectors of the economy. “What I’m almost certain of, from talking with people at senior levels of government, is that if we have a major event involving one of our ports and a container, we will stand down the system,” says Flynn, a senior fellow for national security studies at the Council on Foreign Relations and the principal adviser to the Congressional Port Security Caucus. “We will shut it off until we sort it out. Now, how is the president, when he stands in front of the American people after a very visible and deadly act, going to reassure them that these other containers can roll across our borders and into our ports without worrying about them?”

Sprawling over nearly 25 square miles, the adjoining ports of Los Angeles and Long Beach are the busiest in the United States, together handling 43 percent of the cargo containers entering the country. Crossing the Vincent Thomas Bridge onto the Los Angeles side of Terminal Island, an awesome sight unfolds: scores of towering container cranes frame the skyline, dozens of huge freighters lie at anchor in the harbor or sit at berth, thousands of containers are stacked in enormous asphalt lots, and hundreds of trucks rumble in every direction. If this bustling scene evokes America’s industrial heyday, that impression is somewhat misleading: the place is flourishing precisely because America has ceased producing many goods. If everything you buy these days seems to be manufactured in China, the Philippines, Turkey or Taiwan, you can thank the global container system for bringing it to you.

“The average person has no idea about container shipping and how it affects them,” says Christopher Koch, president and CEO of the Washington, D.C.-based World Shipping Council, whose members transport 93 percent of the containers coming to America. “It’s like asking a kid where electricity comes from, and as far as he’s concerned it comes from turning on a switch. The Nikes on their feet, the shirts in their closet, the spices in their kitchen, the Heineken beer in their refrigerator and the DVD player in their den—all that stuff gets to them because of containers.”

The container cargo system, which began expanding rapidly in the 1960s, has revolutionized world trade, making it possible to load a 40-foot box at a factory in inland China, drive it to Hong Kong, lift the container onto a ship, transport it to Los Angeles, offload it quickly—a box a minute in some cases—and place it on a truck bound for, say, a Wal-Mart in New Mexico. “It has basically made geography increasingly irrelevant as a factor in production and trade,” Flynn said.

The number of incoming containers handled by the ports of Los Angeles and Long Beach jumped some 13 percent from 2001 to 2002, to 2.8 million, and is expected to double over the next decade. Port officials estimate that 40 percent of American trade in some way depends on containers that flow through the Los Angeles-Long Beach complex. How vital the seaports are was felt in 2002, when a labor dispute led to a ten-day lockout of West Coast longshoremen, costing the U.S. economy $1 billion a day.

Before 9/11, customs inspectors devoted their energies to searching for narcotics, commercial contraband and smuggled immigrants. They waded through mountains of paper manifests filled with amorphous terms such as “freight of all kinds” and “said to contain.” Port security was lax, with people able to wander at will in many areas. Capt. John M. Holmes, who recently retired as commanding officer of the Coast Guard at the Los Angeles-Long Beach port complex and is credited with improving security in the harbor, says that airport security, poor as it was before 9/11, was “like Fort Knox compared with our ports.”

Officials have scrambled to plug the holes in the container cargo system, instituting measures that have won qualified praise from security experts and the General Accounting Office. U.S. Customs now requires all shippers to declare their containers’ contents 24 hours before they’re loaded onto a freighter bound for a U.S. port. In addition, the bureau has refined an automated computer system—originally designed to detect narcotics and other contraband—to help identify suspect shipments. Among the many characteristics that the system is supposed to identify are unknown importers, manufacturers or shippers that have never delivered to America before and small shipments from high-risk countries. For example, a load of goods forwarded by a first-time shipper in Pakistan to a new destination in the United States would be almost certain to get the once-over from customs inspectors who work for Vera Adams, the Customs and Border Protection director at the Los Angeles and Long Beach port complex. “The goal is to examine 100 percent of the high-risk stuff,” she says. Customs inspectors in the port complex now perform four times as many physical inspections as before 9/11. Shipping-industry executives say the added examinations have not slowed container commerce.

As part of its Container Security Initiative, launched in January 2002, U.S. Customs and Border Protection has stationed inspectors at 16 foreign ports and plans to send officers to a couple dozen more. The goal is to work with local customs departments to inspect suspicious containers before they’re shipped to America. The customs bureau is also advising several thousand shippers, brokers and manufacturers how to tighten up a supply chain that enables people around the globe to fill containers with whatever they please and, in effect, mail it to the United States. As even the shipping industry acknowledges, this is the major weakness of the system. “The carrier doesn’t load the container,” says the World Shipping Council’s Koch. “It dispatches a container, and the container comes back several days later with a seal on it. The most obvious vulnerability is not containers being tampered with in transit. It’s what’s put in the box in the first place. It’s like the government trying to find out what’s put in every sealed letter given to the post office.”

Worries about the security of the container system surfaced in the early 1990s, when Flynn, among others, pointed out that it was increasingly being used to smuggle drugs, guns and people. In 1998, Flynn first noted that terrorists could exploit the container system to attack the United States. Officials and other security experts began to take that possibility very seriously after 9/11. And topping their list of doomsday scenarios is Al Qaeda using a container to slip a nuclear device into the United States. Would customs inspectors, with current technology, be able to detect a small nuclear weapon hidden in a container? Customs officials, including McCabe, say yes. But some nuclear physicists disagree, saying that a few pounds of shielded, weapons-grade uranium would not give off a strong radioactive signature. “Seeing enriched uranium inside a large, seagoing cargo container is an exceedingly difficult problem,” said Stanley Prussin, a nuclear engineer at the University of California at Berkeley. “There is a wide range of possible cargo loads that would make it very difficult to detect this material.” To be sure, smuggling uranium into the country isn’t enough to make an explosive nuclear bomb; that is a considerable technical task requiring expertise in nuclear science and access to other technology.

U.S. government-sponsored scientists are working on new technologies to improve detection of radioactive materials. At the Lawrence Livermore National Laboratory in Livermore, California, researchers are testing a device that bombards an object with a stream of neutrons, which can penetrate heavy shielding and react with nuclear material. The question is whether scientists can adapt the technology to use in scores of port terminals. “We are actively working to try to develop a methodology that will offer a thousand times greater probability of detection than we have now,” said Prussin, who is a consultant on the Lawrence Livermore project. “Whether this can be done in a practical way, I don’t know.”

But experts contend that the best way to keep a nuclear, chemical or biological weapon out of a United States-bound container is to overhaul the shipping system.

Flynn praises Customs and Border Protection for gaining a beachhead in foreign ports by posting inspectors there. But that presence, he argues, must be expanded so that mom and pop container operations are routinely scrutinized and even trusted shippers are periodically checked. Right now, overseas customs operations are understaffed, and customs requirements are largely voluntary. “To get where we need to go, you’ve got to create incentives and disincentives for the Wal-Marts and Targets and GMs to essentially insist that all the people in their food chain take adequate security precautions and they can track and monitor material,” says Flynn. “The core problem is that everybody knows that customs has no capacity to go and check.” Large manufacturing and shipping operations, like those used by major American companies, may well have to hire security personnel and inspectors to ensure that no one tampers with their shipments.

Security officials also foresee “smart containers” that feature radiation detectors, tamper-proof electronic seals and GPS units to alert dispatchers when containers are diverted. Smaller shippers would be encouraged to use such technology and to pack containers at supervised sites. Those who comply would see their shipments expedited and would undergo fewer inspections at U.S. ports. Those who don’t comply would face delays and mandatory inspections in the United States. “The only way that you’re going to get better behavior upstream is to inflict pain, and that means lots of inspections,” Flynn says. “If you fail the test in terms of compliance, you’re going back in that slow lane for six months. You’ve got to have a heavy hammer as well as an incentive system.”

Such measures would involve spending a great deal more on port security and the creation of a large group of overseas customs inspectors—the equivalent of a Foreign Service for the Department of Homeland Security. Flynn, author of the soon-to-be published book America the Vulnerable: How the U.S. Has Failed to Secure the Homeland and Protect Its People from Terror, is not alone in calling for new initiatives. The General Accounting Office reported last summer that the customs bureau had fallen short, not allocating sufficient manpower or devising effective oversight procedures in its overseas port inspections. So far, the administration has spent about $350 million on port security—a fraction, critics say, of what is needed. The U.S. Coast Guard estimates that $1.5 billion will be needed for port security improvements in 2004.

Most shippers and manufacturers have voiced a willingness to comply with tougher security measures. “The industry is supporting these initiatives because it recognizes the need to build a security infrastructure before a terrorist event,” says Koch of the World Shipping Council. In the event of an attack, a more stringent security system might allow investigators to find the weak link quickly and reopen American ports in a matter of days rather than weeks, saving billions of dollars. That said, not even a beefed-up container network would be immune from terrorism. The volume of containers flowing into the United States is simply too large. “Are we ever going to be invulnerable?” says Adams of the customs bureau at the Los Angeles-Long Beach ports. “No. The only way we’d ever be invulnerable is to shut down the border and become a police state, and then [the terrorists] have won.”

In a high-rise glass building in Long Beach, a customs inspector named Keith Perteet spends his days in front of a computer attempting to fathom whether the tools for America’s next terrorist attack might be hidden in one of the 65,000 containers that pass weekly through the Los Angeles-Long Beach ports. Perteet, a 42-year-old Navy veteran hired in the aftermath of 9/11, scrolls through the electronic invoices received from incoming ships, looking for “anomalies,” such as odd addresses or fuzzy descriptions of cargo. Sliding across his computer screen are the fruits of globalization, things Americans hardly seem to make anymore: cardigan sweaters, shoes, tights, plastic bags, ceramic tiles, marble urns, lighting fixtures, furniture, DVD players.

On the front line is Paul Puletz, a 31-year-old former marine known as one of the most aggressive customs inspectors in Los Angeles-Long Beach. Tall, well-muscled, with closely cropped dark hair and a goatee, the native Virginian wears wraparound sunglasses, a 9 millimeter automatic handgun and black boots polished to a high sheen. He is in the habit of addressing people as “sir” or “ma’am.” As we stood on a Los Angeles dock near a freighter the length of three football fields, a crane—its operator ten stories above us—lifted containers and placed them on yellow-cabbed trailer trucks, which shuttled them around the immense storage yard. Puletz, who has taken antiterrorism courses and studied captured Al Qaeda training manuals, was reflective. “The bad guys have very deep pockets and they are on the offensive,” he said. “Seeing the Al Qaeda handbook, what surprised me was how much their organization is like the military. They’re not just a bunch of desert dwellers. They’re extremely intelligent. They believe in what they’re doing. And they’re patient.”

After spending two days with Puletz as he scanned containers with a gamma-ray machine, inspected boxes of goods, and instructed recruits how to board and search freighters, I came away impressed that he can muster enthusiasm for his job when, day after day, he does not find anything bearing on the bureau’s main task these days: fighting terrorism. “If I go home every night and I’ve made it through another day without something happening in the harbor,” he says, “then I’m happy.”