We have read both sides of the issue of whether or not the United States is justified in conducting preemptive strikes. But really, this is about us making decisions for ourselves and justifying it (or not) to the rest of the world.
For this assignment, you will need to take off your American hat and take a new job at the United Nations. Your job is to create a standard a set of conditions if you will under which any nation in the world may conduct a preemptive attack. What would those conditions be?
Use the cases you have read to write your conditions. They may be more or less strict than the conditions we have explored, but you may not argue that there are no conditions. You will need to also use the United Nations Charter to see exactly where your standards would fit.
The Charter can be found at http://www.un.org/en/documents/charter/