Why did the United States make the decision to cause such devastation? It was not a decision to be made lightly. Here is a website that may help you understand the elements that went into the decision. Here are documents that were a factor in the decision.

A very intriguing essay that looks at various theories for the decision.

The only way anyone can judge Truman’s motives in dropping the atomic bomb is by analyzing the result of his decision. No one can know, even by reading his personal diary, the exact reasons he had for using the bomb. It was likely a combination of many: punishment, justification of cost, saving lives, and ending the war as quickly as possible.