Ever since the attacks of Sept. 11, 2001, officials in Washington and around the world have been warning of more devastating attacks from Islamic militants.
The warnings have been backed up by horrifying incidents. More than 200 people died in a bombing in Bali, Indonesia, in October 2002. A series of bombings in Madrid in March 2004 claimed nearly 200 more lives.
When there is an attack to rival those of Sept. 11, it may not be as dramatic -- but it could be even more deadly and disruptive.
Earlier this year, bioterrorism experts brought governmental leaders from around the world to Washington to take part in a "war game," exploring what would happen if such an attack occurred.
The participants included former Secretary of State Madeleine Albright, playing the U.S. president; Bernard Kouchner, former president of aid organization Doctors Without Borders, playing the French president; and Swedish Ambassador to the United States Jan Eliasson playing the Swedish prime minister. What follows is how it went.
Authorities will never know definitively, but they think the latest terrorist attack came in the chillingly simple form of one of the thousands of commuters who use New York City's bustling Penn Station.
The terrorist was probably equipped with a canister of smallpox the size of a small fire extinguisher, and infected 25,000 people in very little time. Terrorists with smallpox canisters were likely sent to other crowded hubs around the world, such as Istanbul's Grand Bazaar and Germany's Frankfurt Airport, multiplying the damage.
At first, the officials had no idea how many cases would develop. Soon, news broadcasts from several European countries reported outbreaks. Germany announced the formation of special isolation wards in Frankfurt hospitals.
Smallpox was one of the most-feared diseases in history. In the 20th century alone, it had killed 300 million people. But in the 1970s, it was eradicated. There was no way the new cases could be naturally occurring. Authorities knew it was terrorism immediately.
An al Qaeda splinter group claimed responsibility. Doctors struggled to find those who were infected as quickly as possible. But there were no rapid diagnostic tests available.
Coming into Conflict
The world community began to take precautionary measures. They started what is called a ring vaccination program -- first inoculating those most likely to become infected, like health workers and port workers.
Initially, the leaders were told there were 51 reported cases worldwide, and there would be 10,000 in a month.
But then Turkey demanded help from its NATO allies to cover its population of 70 million people. The situation quickly got complicated.
After 9/11, the Bush administration ordered production of more than 300 million doses of smallpox vaccine, one for every American. It would be politically difficult to justify putting any Americans in harm's way without reason.
The U.S. president used the call for help to leverage future cooperation. "When we really needed help in Iraq, many of you decided it was not useful," she said.
The world leaders were informed there were more than 700 million doses of the smallpox vaccine available.
However, that was only enough to inoculate 10 percent of the world population. Even under emergency conditions, it would take 10 years to produce enough vaccine for everyone. Only four companies in the world make the vaccine.
The disease appeared to be spreading faster than expected. Poland and Italy announced infections. Then, an update: There were 240 reported cases worldwide, and a projection said there would be almost 50,000 cases of smallpox by the next month.
New cases also appeared in North America. The spread of the disease accelerated globally: 956 reported cases and a new projection of 200,000 cases by the following month.
To make up for the shortfall in vaccines, the leaders considered diluting them. But diluted vaccines have never been used in a real smallpox epidemic, and past studies on the issue are inconclusive.
There were other attempts to halt the spread. Some considered quarantining the infected. But it would prove almost impossible to enforce. How and when do you declare the quarantine over?
Others considered ordering anyone entering or leaving their country to be screened for fever or rashes. But smallpox symptoms don't present themselves for many days.
Still more argued for closing their borders to prevent an influx of vaccine seekers.
Pilots and union members of other major European and American carriers began threatening to strike unless they receive smallpox vaccinations. A number of carriers announced temporary cancellations of flights into and out of countries with confirmed smallpox cases
Meanwhile, within the United States, a number of states closed their borders. "Nevada, Indiana and Pennsylvania are reporting strong public and political pressure to control their borders, and they don't want anybody coming in from California," said the U.S. president.
By the time the simulation neared its end, there were 3,320 reported cases of smallpox worldwide, with a projection that within a month there would be 660,000 cases.
International commerce and cooperation were breaking down. There was also the threat of more chaos on the horizon. In apparent response to the claim of responsibility by an al Qaeda-linked group, anti-Muslim violence was breaking out. Arsonists attacked two major mosques in the Dutch city of Rotterdam.
"There is a, evidently a plan here to create mass hysteria in the world and to bring the world economy to a halt," observed the Swedish prime minister.
There were more problems than solutions on the table.
Politics of Disaster
Afterwards, Albright said she was glad she participated. "I think it's a very useful exercise because it makes people consider making decisions in real-time and reacting to other people's reactions."
But former counterterrorism czar Richard Clarke, an ABC News consultant, pointed out that the scenario might have been too simple. The world community already recognizes the threat of smallpox, and is in the process of creating countermeasures. If terrorists use a different biological weapon -- like a genetically-altered super bug -- there might be even more chaos.
The SARS outbreak in Southeast Asia showed how connected the world is, and how such an attack could hobble the mobility that is crucial to the global economy, Clarke said. "If something like this happens, a lot of nations are going to just shut down and not let anybody in or anybody out," he said.
Clarke also said he expected the nasty political infighting that occurred inside and outside the United States during the scenario would take place if such an attack happens in real life.
"We saw this with the flu vaccine. If a particular state has a lot of vaccination and another region doesn't, the governor of that state doesn't want the vaccine going to the other part of the country," he said.
Albright agreed, and said that was the most important part of understanding this threat.
"You think, in fact, that the United States is a united place in dealing with this, but not only were there the politics of why you share with foreigners, but there were the politics of sharing inside."