The NSC considers the virus a significant military threat. As a weapon, it could effectively cripple our fast paced mobile world.
"Thousands of people know how to work with the smallpox virus. Where these people are and what they're doing of course nobody knows. It makes me nervous," says former Soviet scientist Dr. Ken Alibek.
In his new book Biohazard, Alibek says smallpox is easy to convert into a weapon. Military and terrorist regimes have mastered the technique of using it to harm people, he says.
He also says the United States is completely unprepared to face smallpox again and is lagging way behind in drug research to treat it.
If a lightbulb sized container was unleashed in the New York City subway system it would infect everyone within hours. Since it takes days for symptoms to show up, people riding the trains could spread the virus anywhere in the country or even the world.
Alibek believes since the smallpox vaccine hasn't been used for 20 years, everyone is susceptible if it were unleashed.
"It wouldn't be an epidemic. It would be a pandemic," he says.
Scientist John Huggins is the only American to do research on smallpox in four years. He has discovered that a drug commonly used to treat herpes is able to stop smallpox in its tracks.
"I think it's quite promising because this is a class of drugs we know a lot about. They're going to lead to even better drugs as we go forward," says Huggins.
The U.S. is still years away from approving a new drug for smallpox. In the meantime the government has plans to start producing more vaccines. This is a crucial step, experts say, toward being prepared for the worst.