What was the immediate impact of the success of the manhattan project?

Firstly, the Manhattan Project is simply a research project that focused on the engineering of atomic bombs. This project helped push through for the so-called "Atomic Age". Because of this project, different discoveries were made such as the proper materials to be used, the mechanics and dynamics of bombs, the use of uranium, etc. However, the immediate impact of the success of the Manhattan Project is not of a good one - it was the death of hundreds of thousands of Japanese people. 

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The answer would be a