The following open letter to Pope Leo XIV was issued on August 19.
We appeal to you, Pope Leo, as the leader who has made the greatest effort to speak for humanity as a whole, instead of for specific nations, religions, or constituencies, to call for an emergency international summit to guide the world away from the current path of war and potential nuclear disaster and to peacefully resolve the greatest crises facing humanity today. Such an effort would be consistent with your repeated calls for peace and justice ever since you assumed the papacy—calls that have inspired and given hope to millions if not billions of people across our planet.
On June 10, 2025, U.S. Director of National Intelligence (DNI) Tulsi Gabbard released a brief but chilling video that began in Hiroshima and warned we are “closer to the brink of nuclear annihilation than ever before” and that “political elite warmongers are carelessly fomenting fear and tensions between nuclear powers.” “It’s up to us, the people,” she concluded, “to speak up and demand an end to this madness. We must reject this path to nuclear war and work toward a world where no one has to live in fear of a nuclear holocaust.”
On October 20, 2025, Sergei Naryshkin, the head of Russia’s SVR foreign intelligence agency, warned, “The world is now experiencing the most fragile moment for international security since World War II.” Naryshkin continued, “Our shared, and perhaps principal, task is to ensure that adaptation to the new reality proceeds without a major war, as has happened at previous historical stages.” It has been many months since the two intelligence chiefs rang the alarm and we’ve only gotten closer to nuclear annihilation—much closer.
When Gabbard and Naryshkin issued those warnings, the war in Ukraine was raging, Israel was conducting its genocide in Gaza, and tensions were high between China and the U.S. over Taiwan and the South China Sea. We have since added the U.S./Israeli war with Iran and the threat of WWIII has thus grown exponentially.
Signs continue to appear that leaders are planning for such an eventuality, even though we have known for more than four decades that even a limited nuclear war, let alone a large-scale one, could unleash unthinkable damage globally, including nuclear winter, which would threaten to end life on our planet. On August 20, 2024, the New York Times ran a front-page article warning that the U.S. was preparing to fight a simultaneous three-front nuclear war against Russia, China, and North Korea. That same day, the Bulletin of the Atomic Scientists reported on a growing school of nuclear strategists who believe a nuclear war can be fought and won, effectively overturning decades of understanding that a nuclear war cannot be won and must never be fought. Last year, U.S. Admiral Thomas Buchanan said that the U.S. was preparing to fight and win a nuclear war and keep enough nuclear weapons in reserve to be able to maintain its global hegemony. More recently, the U.S. Pentagon policy chief Elbridge Colby has discussed the need for the U.S. to use tactical nuclear weapons on top of deploying troops from South Korea and Japan if fighting breaks out between the U.S. and China over the Taiwan Strait.
The experts behind the Bulletin of the Atomic Scientists’ Doomsday Clock are not alone in believing that the world is getting closer and closer to nuclear annihilation. And on top of the threats coming from the U.S., several influential Russian leaders have called on Vladimir Putin to use nuclear weapons in defeating Ukraine.
We, the undersigned from around the world, think the timing is propitious for calling an emergency international summit to address major conflicts in the world and the need for stepping away from the nuclear precipice. Russia has been bogged down in Ukraine for almost five years. Though Russia continues to make incremental gains at great cost, the battlefield has largely stalled and both sides are doing extensive damage to energy infrastructure and shipping in their drone and missile warfare, causing global energy and food shortages and suffering both inside and outside their respective countries. If NATO-backed Ukraine continues to cross Russia’s red lines, will Putin be willing and able to thwart Russia’s hawks? The U.S., meanwhile, has been unable to find a diplomatic escape route from its war with Iran, which shows no sign of allowing the U.S. to end the crisis it and Israel created by attacking Iran. While China insists that retaining Taiwan is its ultimate red line, everyone in the region would benefit from a calming of tension and diverting resources into development, along the lines of China’s Belt and Road initiative, instead of into warmaking.
That last point should be applied universally. It is painfully wasteful to see so many nations diverting resources from food, housing, education, and healthcare to their militaries. This has especially been true in North America, Europe, and Asia where talk of peacefully resolving conflicts has given way to talk of preparing for war.
As you yourself wisely and powerfully stated a couple of months ago, “I have repeated more than once the fervent appeal that Saint Paul VI made to the United Nations Assembly—What unites me, my venerable predecessor noted, is a pact sealed ‘with an oath that ought to change the future history of the world: never again war, never again war! It is peace, peace, that has to guide the destiny of the nations of all mankind’! Above all in the atomic era, the affirmation of the truth must push through: it is not atomic weapons that generate peace, but disarmament. This truth, which seemed clear in past decades when we witnessed a nuclear de-escalation, has been obscured by a race to armament that today frightens and terrifies.”
It was indeed Pope Paul VI, the first pope to address the United Nations in October 1965, who, in that extraordinary address, quoted President Kennedy, “Mankind must put an end to war, or war will put an end to mankind.” He cited the Book of Isaiah, declaring, “They shall beat their swords into plowshares and their spears into pruning hooks.” In his 1967 Encyclical “Populorum Progressio,” Pope Paul VI emphasized, “Development is the new name for Peace.”
Other popes have also taken bold initiatives to save humanity in moments of crisis. In October 1962, Pope John XXIII appealed for peaceful resolution of the Cuban Missile Crisis and helped provide both President Kennedy and Premier Khrushchev with face-saving means to resolve the crisis diplomatically rather than militarily at a moment when war seemed imminent. A similar effort might succeed today when the world’s two major wars seem to be intractably bogged down.(**see Attachment) The same is true of the nuclear arms race as the nine nuclear powers are not only modernizing their arsenals but expanding them after decades of sensible if much too slow reductions. And, for the first time in decades, the two major nuclear antagonists are constrained by no nuclear arms control treaties. Other countries, including Japan, South Korea, Poland, Saudi Arabia, Taiwan, and Ukraine, have begun discussing the attainment of nuclear weapons of their own, which would only turn the world into a larger nuclear tinderbox.
A papal appeal for an emergency summit to end the current wars and reverse the growing dependence on nuclear weapons and warfighting might give global leaders the chance to select a new course of action and get us off the current drive toward planet-destroying nuclear war. We urge you, Pope Leo, to use your unique moral authority to convene such a meeting of the world’s leaders, including the heads of state of the three principal nuclear powers, to meet and respond to the pleas of humanity to take our world in a fundamentally different direction before it is too late.
Initiating Signers,
Peter Kuznick, Professor of History and Director, Nuclear Studies Institute, American University, Washington, DC
