Here is a news link:
Terrorists are “likely” to use nuclear or biological weapons in the next five years, a US commission warned, highlighting Pakistan as the weakest link in world security.
Without urgent action, “it is more likely than not that a weapon of mass destruction will be used in a terrorist attack somewhere in the world by the end of 2013,” the bi-partisan commission said Tuesday in its report “World at Risk.”
The report, ordered by Congress and based on six months of research, warned the incoming US administration of Barack Obama: “America’s margin of safety is shrinking.”
While nuclear terrorism is indeed scary, biological attacks have proven to be very limited in effectiveness and are mainly known for inducing fear. For that matter, the report may (I haven’t seen it) regard a dirty bomb as nuclear terrorism, and such a weapon is mainly effective for creating fear rather than doing damage. So I would be inclined to take the report with a grain of salt.