Deadly germs may be more likely to be spread due to a biodefence lab accident than a biological attack by terrorists.
The 1918 flu virus spread across the world in three months and killed at least 40 million people. If it escaped from a lab today, the death toll could be far higher. Yet despite the danger, researchers in the US are working with reconstructed versions of the virus at less than the maximum level of containment.
A scientist funded by the US government has deliberately created an extremely deadly form of mousepox, a relative of the smallpox virus, through genetic engineering.
The Carnegie Endowment for International Peace has warned that an invasion of Iraq could worsen the terrorist threat, not reduce it. They fear it could disperse weapons stockpiles - and the scientists who can build and use them - into the murky world of global terrorism.
In the aftermath of the terrorist atrocities in the US, governments around the world are urgently reviewing their counter-terrorist measures in anticipation of the vast amounts of government money that is likely to be channelled towards developing better counter-terrorism approaches.
The terrorist attacks on the World Trade Center are forcing a re-evaluation of terrorist response plans which until now, have focused on attacks with nuclear, chemical or biological weapons.
If the US develops a national missile defence system, it could face up to 20 times as many land-based Russian nuclear warheads within six years as it would face without the system.