What lessons were learned, what policies were implemented and at what cost (financially)?

Research three dates in which terrorists have used chemical or biological weapons in their attack. Two of the dates must have occurred in the USA. Detail the plot, motive and reason for the attack. What was the impact on the economy and the country as a whole. What lessons were learned, what policies were implemented and at what cost (financially)? 2-3 pages is the limit! No more than 3 pages in length and no fluff. Just give me the facts!