The Magisterium of the Popes and nuclear weapons

By Andrea Tornielli

Since the tragedy caused by the atomic bombings of Japan in August 1945, the Church has reflected on the risk of humanity destroying itself.

In his Christmas Radio Message of 1955, Pius XII spoke of the nuclear threat, explaining that “there will be no cry of victory, but only the inconsolable weeping of humanity, which will desolately contemplate the catastrophe brought about by its own folly.” In the encyclical Pacem in terris, published immediately after the Cuban Missile Crisis, Pope St. John XXIII stated with regard to atomic weapons: “Consequently people are living in the grip of constant fear. They are afraid that at any moment the impending storm may break upon them with horrific violence. And they have good reasons for their fear, for there is certainly no lack of such weapons. While it is difficult to believe that anyone would dare to assume responsibility for initiating the appalling slaughter and destruction that war would bring in its wake, there is no denying that the conflagration could be started by some chance and unforeseen circumstance."

In June 1968, Pope Paul VI declared: “We again express and implore this hope, in the name of all humanity—for a total ban on nuclear weapons and for general and complete disarmament.” Meanwhile, in February 1981 in Hiroshima, John Paul II cried out: “Our future on this planet, exposed as it is to the risk of nuclear annihilation, depends on one factor alone: humanity must undergo a moral transformation. At this moment in history, there must be a general mobilization of all men and women of good will. Humanity is called to take a further step forward, a step toward civilization and wisdom.” In May 2010, Pope Benedict XVI stated: “I encourage initiatives aimed at progressive disarmament and the creation of nuclear-weapon-free zones, with a view to their complete elimination from the planet.”

From Hiroshima in November 2019, Pope Francis recalled that “the use of atomic energy for purposes of war is, today more than ever, a crime not only against human beings and their dignity, but against any possible future in our common home.” He added: “The use of atomic energy for purposes of war is immoral, just as the possession of nuclear weapons is immoral, as I said two years ago. We will be judged for this. New generations will rise as judges of our failure if we spoke of peace but did not achieve it through our actions among the peoples of the earth. How can we speak of peace while we build new and formidable weapons of war? How can we speak of peace while we justify certain illegitimate actions with rhetoric of discrimination and hatred?”

Pope Leo has continued along the path traced by his predecessors’ magisterium. On 14 June 2025, at the end of the Jubilee Audience, he said: “The situation in Iran and Israel has deteriorated gravely, and in such a delicate moment, I would like to renew strongly an appeal to responsibility and reason. The commitment to creating a safer world, free from the nuclear threat, should be pursued through respectful encounter and sincere dialogue, to build a lasting peace, based on justice, fraternity and the common good. No-one should ever threaten the existence of another.”

Just over a month later, in a message for the 80th anniversary of the atomic bombings of Hiroshima and Nagasaki, Pope Leo wrote: “True peace requires the courage to lay down arms, especially those capable of causing an indescribable catastrophe. Nuclear weapons offend our common humanity and betray the dignity of creation, whose harmony we are called to safeguard.” On 6 August, at the General Audience, recalling the devastation caused in Japan by nuclear devices, he issued this appeal: “Despite the passage of years, those tragic events remain a universal warning against the devastation caused by wars and, in particular, by nuclear weapons. I hope that in today’s world, marked by grave tensions and bloody conflicts, the illusory security based on the threat of mutual destruction will give way to the instruments of justice, the practice of dialogue, and trust in fraternity.”

The current Successor of Peter returned to the issue in his Message for the 2026 World Day of Peace, stating: “In the relations between citizens and rulers, it could even be considered a fault not to be sufficiently prepared for war, not to react to attacks, and not to return violence for violence. Far beyond the principle of legitimate defense, such confrontational logic now dominates global politics, deepening instability and unpredictability day by day. It is no coincidence that repeated calls to increase military spending, and the choices that follow, are presented by many government leaders as a justified response to external threats.  The idea of the deterrent power of military might, especially nuclear deterrence, is based on the irrationality of relations between nations, built not on law, justice and trust, but on fear and domination by force.”

At the end of the audience on 4 February 2026, Pope Leo XIV declared: "Tomorrow marks the expiry of the New START Treaty signed in 2010 by the Presidents of the United States and the Russian Federation, which represented a significant step in containing the proliferation of nuclear weapons. In renewing my encouragement for every constructive effort in favour of disarmament and mutual trust, I urgently call for this instrument not to be abandoned without seeking to ensure its concrete and effective follow-up. The current situation requires that everything possible be done to avert a new arms race that would further threaten peace among nations. It is more urgent than ever to substitute the logic of fear and distrust with a shared ethos capable of guiding choices towards the common good and to make peace a treasure to be cherished by all."

Finally, in a post from the official Pontifex account on 5 March 2026, Pope Leo wrote: “Let us #PrayTogether that nations may move toward effective disarmament, particularly nuclear disarmament, and that world leaders may choose the path of dialogue and diplomacy instead of violence. #PrayerIntention @clicktopray_en”

These are the statements of the Pontiff, who continues to call for the dismantling of all existing nuclear weapons capable of destroying all humanity.