Hoping to hasten the doomsday their leader foretold, scientists who were members of Japan's Aum Shinrikyo cult brewed batches of anthrax in the early 1990s and released it from an office building and out the back of trucks upwind of the Imperial Palace.
But the wet mixture kept clogging the sprayers the Aum Shinrikyo scientists had rigged up, and, unbeknown to them, the strains of anthrax they had ordered from a commercial firm posed no danger to anyone. Frustrated by their failure at biowarfare, they turned to a less arduous method of mass killing -- chemical attack -- and in 1995 killed 12 Tokyo subway riders by releasing sarin gas in the tunnels.
The cult's experiences demonstrate just a few of the myriad technical obstacles that terrorists who might try to manufacture biological weapons could face, problems that would confound even skilled scientists who tried to help them, biological warfare experts say.
Locating virulent anthrax specimens with which to brew an attack-sized batch would be difficult given the medical community's caution about suspicious buyers. Smallpox could be next to impossible to obtain because it is thought to exist in only two secure sites, in Russia and in the United States.
Creating aerosolized microbes also requires expertise in many arcane scientific disciplines, such as culturing and propagating germs that retain their virulence and "weaponizing" them so they float like a gas and enter the lungs easily.
But specialists also say it is all but inevitable that al Qaeda or another terrorist group will gain the expertise to launch small-scale biological attacks and eventually inflict mass casualties. Information on the mechanics of creating bioweapons is easily accessible on the Internet and in technical manuals, and the equipment to do the job is readily found. Many brew pubs, for example, have fermenters that can cook up deadly germs.
Advances in bioscience, and the rapid dissemination of this knowledge worldwide, are making it easier for even undergraduates to create dangerous pathogens. Creating microbe weapons is more challenging than producing the simplest implements of terrorism -- conventional explosives or chemical weapons -- but much less difficult than the most technically daunting -- nuclear weapons -- experts say.
Richard Danzig, a former Navy secretary and now a biowarfare consultant to the Pentagon, said that while there are 1,000 to 10,000 "weaponeers" worldwide with experience working on biological arms, there are more than 1 million and perhaps many millions of "broadly skilled" scientists who, while lacking training in that narrow field, could construct bioweapons.
'Ignorance and inexperience'
"It seems likely that, over a period between a few months and a few years, broadly skilled individuals equipped with modest laboratory equipment can develop biological weapons," Danzig said. "Only a thin wall of terrorist ignorance and inexperience now protects us."
Some agents are simpler than others to weaponize. Toxins such as botulinum, which is not contagious and unlikely to cause mass casualties, are the easiest to turn into weapons, particularly for a food-borne or water-borne attack. Bacterial agents such as anthrax, which also is not contagious, are more difficult to manufacture. Viruses such as smallpox, which is contagious and could kill millions, are tougher still.
The most challenging are some of the new 21st-century bioweapons that scientists contemplate being created in the future -- but experts believe even these compounds are fast becoming easier to produce.
In 2002, a panel of biowarfare experts concluded in a report co-published by the National Defense University (NDU) that while terrorists could mount some small-scale bioattacks, larger assaults would require them to overcome many technical hurdles. Some key biotechnologies would be achievable only three to four years from then, the panel found.
"When we sent out the report for review to [hands-on] bench scientists, we got the response, 'What do you mean we can't do this? We're doing it now,' " said Raymond Zilinskas, a co-author of the report who heads biowarfare studies at the Center for Nonproliferation Studies, a California think tank. "It shows how fast the field is moving."
Those skeptical of the prospect of large-scale bioattacks cite the tiny number of biological strikes in recent decades. Members of the Rajneeshee cult sickened 750 people in 1984 when they contaminated salad bars in 10 Oregon restaurants with salmonella. Among the few others were the 2001 anthrax attacks through the U.S. mail that killed five people.
One reason for the small number of attacks is that nearly every aspect of a bioterrorist's job is difficult. The best chance of acquiring the anthrax bacterium, Bacillus anthracis, is either from commercial culture collections in countries with lax security controls, or by digging in soil where livestock recently died of the disease -- a tactic Aum Shinrikyo tried unsuccessfully in the Australian Outback.
Once virulent stocks of anthrax have been cultured, it is no trivial task to propagate pathogens with the required attributes for an aerosolized weapon: the hardiness to survive in an enclosed container and upon release into the atmosphere, the ability to lodge in the lungs, and the toxicity to kill. The particles' size is crucial: If they are too big, they fall to the ground, and if they are too small, they are exhaled from the body. If they are improperly made, static electricity can cause them to clump.
Laborious trial and error
Making a bug that defeats antibiotics, a desired goal for any bioweaponeer, is relatively simple but can require laborious trial and error, because conferring antibiotic resistance often reduces a bioweapon's killing power. Field-testing germ weapons is necessary even for experienced weapons makers, and that is likely to require open spaces where animals or even people can be experimentally infected.
Each bioagent demands specific weather conditions and requires unforgiving specifications for the spraying device employed. "Dry" anthrax is harder to make -- it requires special equipment, and scientists must perform the dangerous job of milling particles to the right size. "Wet" anthrax is easier to produce but not as easily dispersed.
Experts agree that anthrax is the potential mass-casualty agent most accessible to terrorists. The anthrax letter sent in 2001 to then-Senate Minority Leader Thomas A. Daschle (D-S.D.) contained one gram of anthrax, or 1 trillion spores.
In a 2003 report for the Pentagon, Danzig estimated that if terrorists released a much larger amount of skillfully made anthrax particles under optimal weather conditions in a large city, 200,000 people in an area 40 miles downwind of the release would be infected, and, if untreated, 180,000 of them would die. Smaller numbers would die as far as 120 miles away.
Government officials would probably realize that an attack had occurred a day or two later, when victims began to show up in emergency rooms with flulike symptoms. Guessing the geographical spread of the attack, officials would then order emergency distribution of ciprofloxacin or other antibiotics, which would probably save many lives -- although experts agree the public health response would be likely to be chaotic and possibly ineffective.
For most experts, the most frightening anthrax scenario is an antibiotic-resistant bug, which many say is not far-fetched. It is "one of the big things we're worried about," Philip K. Russell, a top bioterrorism adviser in the Department of Health and Human Services, said in an August interview in the trade journal Biosecurity. "It's my view that we have about three or four years to come up with a solution to multidrug-resistant anthrax. . . . We haven't taken anthrax off the table as a threat that can create a very big disaster."
Government officials also said they accept a Danzig theory that terrorists probably would launch bioattacks against various cities simultaneously or sequentially, using a tactic he calls "reload." Danzig said it would be designed to overwhelm government responses and undermine public confidence in officials.
"Our national power to manage the consequences of repeated biological attacks could be exhausted while the terrorist ability to reload remains intact," he wrote in the Pentagon report.
The 2002 NDU study -- led by Zilinskas and Seth Carus, a biowarfare expert at the university -- concluded that at that time, large-scale bioweapons were less likely to be fashioned by terrorists than by nations such as Iran, or by disgruntled bioscientists. The report also detailed the skill levels necessary to accomplish various biowarfare-related tasks. A "junior scientist," for example, could use genetic engineering to weaponize both bacterial and viral pathogens.
Experts say that since then, the spread of knowledge and the increasing availability of sophisticated equipment have placed more and more complex tasks within the ability of less-skilled people. Some experts expressed concern about the easy availability of inexpensive biological "kits" from commercial catalogues that streamline cloning and other once-daunting tasks.
The Zilinskas-Carus report said it is "chancy" to estimate which weapons terrorists could make after 2005 because of scientists' increasing ability to synthesize and manipulate biological material such as DNA.
"Novel DNA sequences are being designed and inserted into living cells by undergraduates," said Roger Brent, a biowarfare expert who is president of the Molecular Sciences Institute, a leading research group in Berkeley, Calif.
Genetically altered superbugs?
Some scientists doubt terrorists will master genetically altered superbugs. But Brent and other experts raise the specter of terrorists' hiring scientists who can insert a toxin into, say, a bioengineered SARS virus, which would then be as contagious as severe acute respiratory syndrome and as fatal as the toxin inside it.
Last year, Brent told a study panel convened by the CIA that current biological capability resembles the capacity of computers in 1965, or English cotton mills in the 1800s -- technologies on the cusp of explosive growth. He said the day is coming when not only terrorists but "garage hackers" will be able to assemble bioweapons.
The CIA panel's late 2003 report, "The Darker Bioweapons Future," said that "the same science that may cure some of our worst diseases could be used to create the world's most frightening weapons. The know-how to develop some of these weapons already exists."
Even banned viruses such as smallpox might be employed one day by terrorists who sidestep the difficulty of obtaining them by synthesizing agents that resemble them, Brent told the panel. "Once synthesized," he said, they "can be grown in indefinite quantities."
"The Rubicon has already been crossed and the process of creating novel genetically engineered orthopoxviruses [diseases including smallpox] is irrevocable," Ken Alibek, a former Soviet bioscientist who defected to the United States, wrote recently in a scholarly journal. "It is just a matter of time before this knowledge will result in the creation of super-killer poxviruses." He added: "If a threat, no matter how small, of a smallpox attack exists, it must be addressed" by developing smallpox detection systems and medicines.
"The alternative," Alibek wrote, "is to remain as helpless as the millions of people who died of smallpox over previous centuries."