What is the weakest argument against using the atomic bomb? Why?

Argument 1: The Bomb Was Made For Defense Only

Argument 2: Use of the Bomb was Illegal

Argument 3: Use of the Atomic Bombs Was Racially Motivated

There Were Alternatives ... most people said that we as a nation could have used other resources to end the war against japan ... it was also considered unseemly to bomb not only active militants but women and children too.