ROME — Marking the 70th anniversary of the use of nuclear bombs by the United States in Japan at the close of World War II, Pope Francis reiterated the Vatican’s long-standing call for a total ban on nuclear arms and other weapons of mass destruction.

The pontiff called nuclear weapons a “symbol of mankind’s enormous destructive power when it makes distorted use of scientific and technical progress.”

Speaking to pilgrims gathered in St. Peter’s Square Sunday, Francis said the US detonation of atomic weapons in Hiroshima and Nagasaki, Japan, “still arouses horror and repulsion,” adding that it “serves as a lasting warning to humanity so that it rejects war and bans nuclear weapons and all arms of mass destruction.”

Above all, the pope said, this “sad anniversary” urges humanity to pray and strive for peace, to spread brotherhood throughout the world, and to promote peaceful coexistence between peoples.

“May one cry rise up from every land: ‘No’ to war and violence and ‘Yes’ to dialogue and to peace,” he said.

An estimated 130,000 people died as a result of the two explosions in 1945, acts which to date remain the only use of nuclear weapons in history. A similar death toll was registered in the following months as a result of burns, radiation sickness, and other injuries linked to the blasts.

In both cities, most of the dead were civilians.

As a Jesuit, Francis has a particular soft spot for what happened in Hiroshima on Aug. 6, 1945, when at 8:15 a.m. an American plane, the Enola Gay, dropped a bomb dubbed “Little Boy,” which fell to a predetermined detonation height of about 1,900 feet above the city.

The bomb vaporized practically everything and everyone within a radius of about a mile of the point of impact, blasting more than two thirds of the city’s buildings into rubble.

Less than a mile from the ground zero, one building remained standing, with its eight inhabitants unharmed: a small community of Jesuit priests living in a presbytery near a parish church. They were among the few to survive the blast, and none suffered ill effects from radiation.

Those survivors included the worldwide superior of the Jesuit order, the Rev. Pedro Arrupe, a figure well-known to the future pope. In 1973, Arrupe would tap the young Jorge Mario Bergoglio, today Pope Francis, as provincial superior of the Jesuits in Argentina.

Another survivor, German Rev. Hubert Schiffer, told his story 31 years later at the Eucharistic Congress in Philadelphia in 1976. Asked why the priests were spared when so many others died either from the explosion or from the subsequent radiation, Schiffer said they were convinced it was because they prayed the rosary daily.

The Vatican has long advocated verifiable mutual disarmament. In the 1965 document Gaudium et Spes (“Joy and Hope”), the Second Vatican Council declared that “any act of war aimed indiscriminately at the destruction of entire cities or extensive areas along with their population is a crime against God and man himself.”

“It merits unhesitating condemnation,” the bishops at Vatican II said.

However, the first Vatican condemnation actually came the day after detonation of the first bomb.

L’Osservatore Romano, the Vatican’s newspaper of record, wrote about atomic weapons on Aug. 7, 1945, denouncing a “catastrophic conclusion” of the war, and describing the atomic bomb as an “incredibly destructive weapon [that] remains as a temptation for posterity, which we know by bitter experience, learns so little from history.”