This post is part of the series on Civil liberties. In an earlier post in this series I promised to discuss the threat from weapons of mass destruction. In this post I do just that.
There are three types of WMD: Nuclear, Biological and Chemical. The first thing to point out is that there has never been a successful deployment of these weapon types by terrorists (Small scale attacks only). Hence any argument for restricting civil liberties on the basis of a WMD threat needs *very* good evidence that such a threat is credible.
The usage of highly contagious disease in a biological weapon is not sensible because the bacteria will cause a global pandemic. Such a weapon would kill not just those of the country in which it was released but all over the world too. Because of this biological weapons must infect most of the people they plan to attack directly and not rely on the spread of the disease itself.
All three types of weapon need sophisticated technology to be successfully deployed. Because of this it is likely that any terrorist group that were to use such a weapon would have either stolen the weaponry from a state or have been support by the state. In either case the international community would be likely to hold that state responsible for the attack. 9/11 is an example of this. The terrorist attack (whilst not of the scale of a WMD strike) precipitated the overthrow of a government which chose to harbor the terrorists responsible.
It is notable that nuclear warheads have only been used as a weapon of war twice. The logic of mutually assured destruction has remarkably prevented any further use of these weapons. The same is likely to be true of any effective biological/chemical WMD ever developed. Because of this we are unlikely to see WMDs used by terrorists any time soon.
There is one, totally irrelevant, point I would like to raise though with regards to biological weapons. A property of pure AIs is that they are very easy to clone. Furthermore computer hardware (if backed up) is much more resilient to software attacks than humans are resilient to biological attacks. Because of this in the event of an advanced AI political grouping waging war on humans the AIs could use biological warfare with multiple highly contagious diseases without having to worry about retribution in kind. Indeed together with the maneuverability of AIs compared to humans (data can travel at close to the speed of light) its difficult to see how humanity could possibly win such a war.