ACA’s journal, Arms Control Today, remains the best in the market. Well focused. Solidly researched. Prudent.

– Hans Blix,
former IAEA Director-General

Papal Condemnation of Nuclear Deterrence and What Is Next
Share this

May 2018
By Gerard Powers

At a major Vatican symposium last year, Pope Francis became the first pope to condemn explicitly not only the use of nuclear weapons but also the “the threat of their use, as well as their very possession.”1

The pope’s statement was praised by many of the 11 Nobel Peace Prize laureates and 300 church leaders, diplomats, scholars, and civil society representatives at the symposium on November 10–11, 2017. His statement and the conference were intended, in part, to further the momentum of the Treaty on the Prohibition of Nuclear Weapons, which the Holy See had ratified on September 20, 2017, the first day it was open for signature. Predictably, critics have responded to the pope’s statement much as they did the treaty, dismissing it as naïve and utopian, a normative judgment largely irrelevant to the realities of the nuclear predicament.

Pope Francis addresses the crowd in St. Peter’s Square at the Vatican, shortly after celebrating Easter Mass. (Photo: ALBERTO PIZZOLI/AFP/Getty Images)The critics seem to have a point, at least for now, as massive nuclear modernization programs, faltering arms control measures, and nuclear brinksmanship harken back to the Cold War era. Yet, the Vatican tends to play the long game. Given its influence as a norm entrepreneur on nuclear weapons and a major transnational actor headed by an influential pope, the critics might want to pay attention.

Deterrence to Disarmament

The November statement is not a major change in the church’s position on nuclear weapons, as has been widely reported. Every pope in the seven decades since Hiroshima, as well as innumerable church documents, have sought to marginalize nuclear weapons and have insisted on the need for progress toward mutual, verifiable nuclear disarmament. The pope’s condemnation of nuclear use is consistent with the church’s long-standing position that the use of nuclear weapons almost certainly would be indiscriminate or disproportionate, risk escalation to nuclear war, cause irreversible harm to the environment, and would break the nuclear taboo, undermining prospects for nonproliferation and disarmament.

What is a departure of sorts is the pope’s condemnation of deterrence. In 1982, Pope John Paul II enunciated an “interim ethic” on nuclear deterrence: “In current conditions,” he said, “‘deterrence’ based on balance, certainly not as an end in itself but as a step on the way toward a progressive disarmament, may still be judged morally acceptable.”2 Pope Francis has now made a prudential moral judgment, based on his reading of today’s very different signs of the nuclear times, that the strict conditions for the moral acceptability of deterrence are not being met. He has not abandoned his predecessor’s formula, but has applied it to current conditions and come to a different prudential moral judgment.

Although Pope Francis’ customary clarity in making this judgment has received considerable attention, it is not significantly different in substance from Vatican statements since the end of the Cold War. In his 2006 World Day of Peace message, Pope Benedict said that the view that states need nuclear weapons for their security is “not only baneful but also completely fallacious.”3 In 2010, Archbishop Celestino Migliore, the Holy See’s permanent observer to the United Nations, referred to John Paul’s interim ethic and concluded that, because “nuclear deterrence is preventing genuine nuclear disarmament…the conditions that prevailed during the Cold War, which gave a basis for the church’s limited toleration of nuclear deterrence, no longer apply.”4 In a similar vein, a 2014 study document released by the Vatican concluded that because the disarmament condition for the moral acceptability of deterrence was not being met, “the very possession of nuclear weapons, even for purposes of deterrence, is morally problematic.”5

These and many other official statements have long made it clear that the nuclear powers could take no more comfort in the church’s position on nuclear weapons before the pope’s November statement than they can now. The interim ethic on deterrence was always a function of context, not time. The Holy See’s reading of the changing geopolitical signs of the times has led it to make a prudential moral judgment that time is up on the interim ethic.

One sign of the times is the judgment that the nuclear powers did not take full advantage of the historic opportunity afforded by the end of the Cold War. The Holy See has welcomed the deep cuts in U.S.-Russian nuclear stockpiles. Nevertheless, the “peace dividend” that was supposed to come with these deep cuts has not materialized. Arms control initiatives have stalled, the nuclear-weapon states have not upheld their end of the nuclear Nonproliferation Treaty’s (NPT) grand bargain, the Comprehensive Test Ban Treaty (CTBT) has not gone into effect, and major nuclear powers have embarked on massive modernization programs.6 Therefore, the Holy See has concluded that nuclear deterrence has not been used as a step toward disarmament but has become an end in itself, a principal impediment to disarmament.

North Korea and the 9/11 terrorist attacks are emblematic of a second sign of the nuclear times. According to the 2014 Vatican study document, “[T]he structure of nuclear deterrence is less stable and more worrisome than at the height of the Cold War” due to continued nuclear proliferation and the increased risk of nuclear weapons use, including by terrorists and unstable nuclear-armed states.7 At the same time, nuclear weapons are increasingly irrelevant in the face of terrorism, cyberwarfare, intrastate conflicts, and other major security threats.

These developments have only reinforced the Holy See’s longstanding concerns about the morally problematic nature of deterrence theories based on a conditional intention to use nuclear weapons in indiscriminate and disproportionate ways and the injustice involved in wasting scarce resources on these weapons instead of devoting them to integral human development.

One cannot understand the Holy See’s position now or during the Cold War solely in terms of these ethical and policy considerations, however important they might be. In his November address, Pope Francis cited Pope John XXIII’s understanding of “integral disarmament,” which is far more capacious than conventional understandings of the term.8

Archbishop Paul Richard Gallagher, the Holy See's secretary for Relations with States, signs the Treaty on the Prohibition of Nuclear Weapons, at the United Nations on September 20, 2017.  At the same time, he handed over the instrument of ratification. (Photo: Darren Ornitz/ICAN)Integral disarmament assumes that the long-term goal of abolishing nuclear weapons has to be part of a much larger cosmopolitan project of developing a global ethic of peace and solidarity that can ground a system of cooperative security. A realist approach that prioritizes a negative peace, defined largely in terms of military security and balance of power, is based on a mentality of fear and the false security of weapons of mass destruction. Nuclear weapons are an impediment to the kind of cooperative security needed to build a positive peace based on a host of factors: socioeconomic development, political participation, respect for fundamental human rights, strong international norms and institutions, a spirit of dialogue, solidarity in international relations, as well as a change of hearts.9

Although the label would not seem to fit a tradition-bound Roman Catholic Church, the Holy See’s articulation of a moral judgment on nuclear use and deterrence, in the context of a wider vision of a radically transformed world based on conceptions of cooperative security and positive peace, makes the church what political scientists call a “norm entrepreneur.”

Nuclear Ban Strategy

As a norm entrepreneur embracing integral nuclear disarmament, it is not surprising that the Holy See was willing to join its religious-moral voice to the legal-political strategy to delegitimize the nuclear status quo and democratize the nuclear debate through the humanitarian impact conferences and the nuclear weapons prohibition treaty.

At the third of these conferences in Vienna in December 2014, Pope Francis issued a major letter accompanied by a study document, a lengthy moral and policy argument for nuclear disarmament. Furthermore, he included a strong appeal for progress on nuclear abolition in his September 2015 address to the UN General Assembly, his January 2017 World Day of Peace message, and his March 2017 letter to the UN conference negotiating the prohibition treaty. These papal interventions complemented a host of interventions by Vatican officials, especially during the ban treaty negotiations.

The nuclear weapons prohibition treaty takes a page from the landmine treaty’s “coalition of the willing” strategy. These norm entrepreneurs—non-nuclear-weapon states, the International Committee of the Red Cross, UN agencies, religious bodies, and nongovernmental organizations—have sought to reframe the nuclear debate, shifting the focus from national security to moral, legal, and humanitarian concerns. This reframing in normative terms reflects a strategic judgment that the current stalemate on nuclear disarmament could only be broken if new international mechanisms were found to stigmatize nuclear weapons and delegitimize the nuclear status quo.

The limitations of this strategy are obvious. It circumvented established processes, and its normative significance is in doubt given the opposition by nuclear-weapon states and most states under their nuclear umbrellas. While acknowledging these limitations, the Holy See, like others behind this strategy, concluded that it was a reasonable step in a complex and long-term process of moving toward a world without nuclear weapons. According to Pope Francis, the treaty “fill[s] a significant juridical lacuna, inasmuch as chemical weapons, biological weapons, anti-human mines and cluster bombs are all expressly prohibited by international conventions.”10

This strategy helps break through the stalemate in bilateral and multilateral negotiations. It will not encourage forum shopping, but rather complements the NPT, CTBT, and other treaties. The Holy See has been quite critical of the morally untenable double standard in the NPT, which perpetuates an unjust, unequal, and dangerous nuclear status quo.11 The prohibition treaty reinforces this critique and helps pressure the nuclear-weapon states to abide by their disarmament obligations under NPT Article VI.

The Holy See’s contributions to the treaty negotiations reflect its priorities.12 First, it successfully pressed for incorporating moral language (“the ethical imperative for disarmament”) into the preamble against the legal positivists who sought to exclude it. Second, it supported language about the “waste of economic and human resources” on nuclear weapons. Third, citing the relevance of nuclear weapons to the global common good, it supported the need for creating a new international authority other than the over-stretched International Atomic Energy Agency (IAEA) to administer and implement the treaty. Fourth, the Holy See supported mention of the moral responsibility of states that had used or tested nuclear weapons to assist with victim assistance and environmental remediation, but recommended a voluntary international fund so as not to stimulate further resistance from nuclear-weapon states. Fifth, the Holy See suggested deleting “any” with respect to the catastrophic consequences and legality of the use of nuclear weapons in order to acknowledge the variety of types of weapons and their potential uses. Finally, the Holy See made a half-dozen different proposals to place nuclear disarmament in the broader context of general disarmament and a positive peace, but succeeded only in including peace education alongside disarmament education.

This last point, about the importance of peace and disarmament education, reflects the Holy See’s conviction that the nuclear debate has to be democratized. According to Pope Francis, filling a legal gap was even more important than the treaty’s inclusiveness, the product of “a significant alliance between civil society, states, international organizations, churches, academies and groups of experts.”13

The humanitarian impact initiative and the nuclear weapons prohibition treaty process ensured that the normative concerns for the global common good expressed by the majority of states were not overridden, as they typically have been, by the national interests of the nuclear-weapon states. These processes also gave a greater voice to civil society, which will be so important in garnering public support for the ban treaty, especially in nuclear-weapon states.

Looking Ahead

The Holy See is in the unique position of being the world’s smallest nation-state and the world’s largest religious institution. Its role in the nuclear debate reflects the strengths and limitations of both roles. As a state, it is not surprising that its policy agenda is similar to that of other non-nuclear-weapon states, and that policy agenda is not likely to change significantly now that there is a prohibition treaty.

The Holy See will continue to routinely addresses issues before the IAEA, the Conference on Disarmament, and other international forums. It will continue to join other non-nuclear-weapon states in supporting full implementation of the NPT, including Article VI; a host of other arms control measures, such as the CTBT and a fissile material cutoff treaty; and stronger mechanisms for the IAEA to prevent proliferation, strengthen nuclear safeguards, and enforce arms control agreements.

The Holy See’s most important and distinctive contributions, however, will be less in policy advocacy and more in its ongoing efforts as a religious institution to help ensure that morality is not an uninvited guest at an exclusive party dominated by realists. Amid the irresponsible nuclear saber rattling of North Korean leader Kim Jong Un, U.S. President Donald Trump, and Russian President Vladimir Putin and the ambitious programs to develop smaller, smarter, and more usable nuclear weapons, the Holy See will continue to do its part to complement the prohibition treaty and strengthen the nuclear taboo against use with its clear moral condemnations.

The longer-term and less direct impact will be on deterrence and disarmament. The pope’s moral condemnation of deterrence, which echoes the legal prohibition in the treaty, should be of concern to nuclear-weapon states because the credibility of deterrence depends in part on the moral credibility of the threats involved. Nuclear policies, at least in democracies, cannot survive in the long term if major religious bodies and the general public lose faith in their ultimate moral legitimacy.

Religious appeals on the moral imperative of long-term efforts of nuclear disarmament are not new, but the narrative has changed over the past 20 years as moral, legal, and policy arguments for nuclear disarmament have gone mainstream, with the prohibition treaty being the most recent example. The Holy See is helping to provide the moral vision of a possibility that can scarcely be imagined now. But more is needed.

The credibility of that vision will depend on addressing two dimensions of an ethics gap. First is to elaborate on the pastoral implications of the pope’s prudential judgment that nuclear deterrence is no longer morally acceptable. If nuclear weapons are illegitimate but nuclear disarmament is not achievable in the near future, what is the moral responsibility of Catholic politicians, soldiers, and citizens in nuclear-weapon states who approve defense budgets, work in the nuclear military, and vote for those advocating a strong nuclear deterrent?

Second, the policy debate on nuclear disarmament is now ahead of the moral debate. Catholic scholars, policy specialists, and religious leaders need to collaborate in developing an ethic of nuclear disarmament that is as sophisticated as the ethic of nuclear use and deterrence developed during the Cold War.14 Many questions should be considered, such as what forms of deterrence would be morally acceptable and effective if the world moved to a minimal deterrent, with its tendency to revert to the counter-population targeting that the church has unequivocally condemned, or if the world actually abolished all nuclear weapons, making possession of illicit nuclear weapons even more valuable, more usable, and more destabilizing? Would a world without nuclear weapons require the development of an ethic of “disarmament intervention” akin to humanitarian intervention to deal with rogue states attempting a nuclear breakout?

Nuclear Weapons and the ‘Mentality of Fear’

The following is an excerpt from the address by Pope Francis on November 10, 2017, to participants in the international symposium “Prospects for a World Free of Nuclear Weapons and for Integral Disarmament,” held at the Vatican.

“In this symposium, you have met to discuss issues that are critical both in themselves and in the light of the complex political challenges of the current international scene, marked as it is by a climate of instability and conflict. A certain pessimism might make us think that “prospects for a world free from nuclear arms and for integral disarmament,” the theme of your meeting, appear increasingly remote. Indeed, the escalation of the arms race continues unabated; and the price of modernizing and developing weaponry, not only nuclear weapons, represents a considerable expense for nations. As a result, the real priorities facing our human family, such as the fight against poverty; the promotion of peace; the undertaking of educational, ecological, and health care projects; and the development of human rights, are relegated to second place.

Nor can we fail to be genuinely concerned by the catastrophic humanitarian and environmental effects of any employment of nuclear devices. If we also take into account the risk of an accidental detonation as a result of error of any kind, the threat of their use, as well as their very possession, is to be firmly condemned, for they exist in the service of a mentality of fear that affects not only the parties in conflict but the entire human race. International relations cannot be held captive to military force, mutual intimidation, and the parading of stockpiles of arms. Weapons of mass destruction, particularly nuclear weapons, create nothing but a false sense of security. They cannot constitute the basis for peaceful coexistence between members of the human family, which must rather be inspired by an ethics of solidarity. Essential in this regard is the witness given by the hibakusha, the survivors of the bombing of Hiroshima and Nagasaki, together with other victims of nuclear arms testing. May their prophetic voice serve as a warning, above all for coming generations!

Furthermore, weapons that result in the destruction of the human race are senseless even from a tactical standpoint. For that matter, while true science is always at the service of humanity, in our time we are increasingly troubled by the misuse of certain projects originally conceived for a good cause. Suffice it to note that nuclear technologies are now spreading, also through digital communications, and that the instruments of international law have not prevented new states from joining those already in possession of nuclear weapons. The resulting scenarios are deeply disturbing if we consider the challenges of contemporary geopolitics, like terrorism or asymmetric warfare.

At the same time, a healthy realism continues to shine a light of hope on our unruly world. Recently, for example, in a historic vote at the United Nations, the majority of the members of the international community determined that nuclear weapons are not only immoral, but must also be considered an illegal means of warfare. This decision filled a significant juridical lacuna, inasmuch as chemical weapons, biological weapons, anti-human mines, and cluster bombs are all expressly prohibited by international conventions.  Even more important is the fact that it was mainly the result of a “humanitarian initiative” sponsored by a significant alliance between civil society, states, international organizations, churches, academies, and groups of experts.

[P]rogress that is both effective and inclusive can achieve the utopia of a world free of deadly instruments of aggression, contrary to the criticism of those who consider idealistic any process of dismantling arsenals. The teaching of John XXIII remains ever valid. In pointing to the goal of an integral disarmament, he stated, “Unless this process of disarmament be thoroughgoing and complete, and reach men’s very souls, it is impossible to stop the arms race, or to reduce armaments, or—and this is the main thing—ultimately to abolish them entirely.”

More moral clarity on these and other issues would reinforce and complement the legal arguments that must be marshalled for the prohibition treaty to gain broader adherence and for sustaining the decades-long process of negotiating and implementing a follow-on convention on nuclear disarmament.

If one of the goals and outcomes of the humanitarian initiative and the landmine ban treaty was to help democratize the nuclear debate, the challenge for the Catholic Church and other religious institutions and civil society actors is to revitalize engagement on an issue that has largely been ignored since the 1980s. As with anti-nuclear mobilization in the 1980s and the current Global Zero campaign, religious institutions will probably not be in the lead. Yet, they can use their vast institutional infrastructure of parishes, dioceses, schools, universities, religious orders, lay organizations, and media to mobilize and motivate around nuclear issues and give added weight to these initiatives.

That has been difficult to do for the past three decades as the nuclear issue moved to the margins of international affairs and understandably receded in the public consciousness. With the exception of the United States, Japan, and Scotland, even episcopal conferences have tended to leave the nuclear issue to the Holy See.

With the prohibition treaty and a return to nuclear tensions and massive modernization programs, some of the ingredients for new anti-nuclear mobilization are in place. The Vatican symposium, a convening of Catholic leaders from Europe and the United States in London in 2016,15 a joint statement by European and U.S. bishops’ conferences in 2017,16 and other developments suggest that the church is poised to re-engage in a significant way. It is not naïve to hope that, as it does so, it can have the kind of influence it had on President Ronald Reagan and his advisers.17 Catholic and other religious voices in Europe could also reinforce opposition to NATO’s current nuclear modernization programs.

The large, high-profile Vatican symposium showed that Pope Francis is moving the moral imperative of nuclear disarmament back to the center of the church’s international agenda. The challenge for the church is to close the ethics gap and strengthen its capacity to continue to inject morality into the nuclear debate and democratize that debate. As with other entrepreneurial endeavors, that will require a new generation of religious leaders, scholars, and professionals with the competence and interest to contribute to the policy and ethical debate on nuclear disarmament.



1. Pope Francis, Address to international symposium “Prospects for a World Free of Nuclear Weapons and for Integral Disarmament” (The Vatican, November 10, 2017), https://w2.vatican.va/content/francesco/en/speeches/2017/november/documents/papa-francesco_20171110_convegno-disarmointegrale.html (hereinafter Vatican symposium).

2. “Message of His Holiness Pope John Paul II to the General Assembly of the United Nations,” June 7, 1982, https://w2.vatican.va/content/john-paul-ii/en/messages/pont_messages/1982/documents/hf_jp-ii_mes_19820607_disarmo-onu.html.

3. Pope Benedict XVI, “In Truth, Peace,” December 8, 2005, https://w2.vatican.va/content/benedict-xvi/en/messages/peace/documents/hf_ben-xvi_mes_20051213_xxxix-world-day-peace.html.

4. Archbishop Celestino Migliore, Lecture at the Woodstock Theological Institute at Georgetown University, March 16, 2010. For a summary of the talk, see Thomas Reese, “Vatican Questions Nuclear Deterrence,” May 12, 2010, http://berkleycenter.georgetown.edu/posts/vatican-questions-nuclear-deterrence.

5. Permanent Mission of the Holy See to the United Nations and Other International Organizations in Geneva, “Nuclear Disarmament: Time for Abolition,” December 8, 2014, p. 4, www.fciv.org/downloads/Holy%20See%20Contribution-Vienna-8-DEC-2014.pdf (hereinafter study document).

6. Archbishop Dominique Mamberti, Statement at the High-Level Meeting of the 68th Session of the General Assembly on Nuclear Disarmament, September 26, 2013, http://www.vatican.va/roman_curia/secretariat_state/2013/documents/rc-seg-st-20130926_mamberti-nuclear-disarmament_en.html.

7. Study document, p. 3.

8. Pope John XXIII, Pacem in Terris, April 11, 1963.

9. Pope Francis, Letter to president of UN conference to negotiate a legally binding instrument to prohibit nuclear weapons, March 23, 2017, https://w2.vatican.va/content/francesco/en/messages/pont-messages/2017/documents/papa-francesco_20170323_messaggio-onu.html.

10. Vatican symposium.

11. Study document, pp. 8-9.

12. See Drew Christiansen, “The Vatican and the Ban Treaty,” Journal of Catholic Social Thought, Vol. 15, No. 1 (2018): 89-108.

13. Vatican symposium.

14. For a more detailed explanation of this gap, see Gerard F. Powers, “The Nuclear Ethics Gap: Finding Our Way on the Road to Disarmament,” America, May 17, 2010, p. 11.

15. The event was titled “Colloquium on Catholic Approaches to Nuclear Proliferation and Disarmament” and was held at the University of Notre Dame London Centre and the Millbank House on May 24-25, 2016. See Catholic Peacebuilding Network, “Colloquium on U.S.-European Approaches to Nuclear Disarmament,” n.d., https://cpn.nd.edu/news-events/past-events/london-2016/ (accessed April 8, 2018).

16. Archbishop Jean-Claude Hollerich and Bishop Oscar Cantú, “Nuclear Disarmament: Seeking Human Security,” Justitia et Pax Europa and U.S. Conference of Catholic Bishops, July 6, 2017, http://www.usccb.org/issues-and-action/human-life-and-dignity/war-and-peace/nuclear-weapons/nuclear-disarmament-seeking-human-security-2017-07-06.cfm.

17. Lawrence J. Korb, “The Vatican Tries to Reduce the Revived Global Threat of Nuclear War,” Bulletin of the Atomic Scientists,
December 13, 2017, https://thebulletin.org/vatican-tries-reduce-revived-global-threat-nuclear-war11346.

Gerard Powers is director of Catholic peacebuilding studies at the Kroc Institute for International Peace Studies in the Keough School of Global Affairs at the University of Notre Dame. From 1987 to 2004, he was an adviser on nuclear issues for the U.S. Conference of Catholic Bishops.

Posted: May 1, 2018