The Pontiff also recalled that, during a nuclear explosion, “processes of unimaginable violence occur over many square kilometers on the earth’s surface, with the volatilization of materials and total destruction due to direct radiation, temperature and mechanical action, while an enormous amount of radioactive materials of different half-lives complete and continue the ruin by their activity.”
As a result, he explained, “entire cities, even among the largest and richest in history and art, annihilated; a black cloak of death over the pulverized matter, covering countless victims with their burned, twisted, scattered limbs, while others moan in the anguish of agony.”
He added: “Meanwhile, the specter of the radioactive cloud prevents any merciful aid to the survivors, and moves inexorably to suppress surviving lives. There will be no cry of victory, but only the inconsolable cry of humanity, which will contemplate desolately the catastrophe due to its own madness.
His successor, Saint John XXIII, the Pope who led the Church during the Soviet missile crisis in Cuba in 1962, also warned of the danger of nuclear weapons in his encyclical. Peace on Earth and demanded “that the arms race stop now.”