The two lines reflect the use of the atomic bomb as a lesser evil than the Axis powers are, where he mentions that they have used it to shorten the suffering of war and protect Americans.
President Harry Truman address the citizens of the country to make them aware of the bombing of Hiroshima and confirms his promise to use more atomic bombs on Japan unless it surrenders.
In their speech, he addresses that they just use the atomic power to safeguard their citizens and ensure their safety whereas the Axis powers used it for threatening the others as it is destructive. Japan, Germany, and Italy were Axis Powers with their seized territories whereas France and its empire were Allied Powers.
Therefore, they used it to safeguard Americans and end the war by minimum casualties.
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