Catholic moral theologians have consistently held that the atomic bombings of Hiroshima and Nagasaki by the United States during World War II were gross violations of justice. The Church herself has taught this:
"Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation." A danger of modern warfare is that it provides the opportunity to those who possess modern scientific weapons—especially atomic, biological, or chemical weapons—to commit such crimes (CCC 2314).
The Church and human reason assert the permanent validity of the moral law during armed conflicts. Practices deliberately contrary to the law of nations and to its universal principles are crimes (CCC 2328).
