University of Notre Dame
Kroc Institutde for International Peace Studies

Gerard F. Powers

In 1983, at the height of the Cold War, the U.S. Catholic Bishops issued a pastoral letter on nuclear weapons, The Challenge of Peace, which is still considered a seminal analysis of the ethics of nuclear weapons. The bishops concluded that most conceivable uses of nuclear weapons would likely violate norms of civilian immunity and proportionality, but they did not conclude that nuclear weapons are inherently immoral. Rather, they proposed an “interim ethic” whereby nuclear deterrence could be morally acceptable if:

(1) it was limited to deterring the use of nuclear weapons and not expanded to include nuclear-war fighting strategies;
(2) sufficiency, not nuclear superiority, was the goal; and
(3) deterrence was a step toward progressive disarmament (i.e., a mutual, verifiable ban on nuclear weapons).

Today, a chorus of prominent military and political figures endorses the goal of progressive nuclear disarmament.


A policy goal of mutual, verifiable nuclear disarmament will have a firmer moral foundation if the arms control criteria (no nuclear-war fighting and no nuclear superiority) are tied to it. The United States has not ruled out the first use of nuclear weapons, even against non-nuclear threats (conventional, chemical, and biological). And the U.S. nuclear arsenal — while nowhere near as massive as in 1983 — remains bloated in terms of any actual or foreseeable nuclear threats, thus failing the criterion of sufficiency.

In addition, just as a strictly conditioned moral acceptance of deterrence is only an “interim ethic,” the moral and legal double standard underlying the Non-Proliferation Treaty (in which some states hold nuclear weapons and others do not) should be seen as a temporary condition. Maintaining a non-nuclear norm (disarmament) that is not universally applicable to all states is morally and politically incoherent and unsustainable.


Politically and militarily, the non-nuclear norm (disarmament) and the non-proliferation norm are not always self-reinforcing and might sometimes even be in conflict. Some moral dilemmas are magnified as one moves toward zero. Would the military and political utility of nuclear weapons — and hence the incentive to obtain weapons and use them — increase as states proceed toward disarmament? Would the end of extended deterrence lead countries like Japan to obtain nuclear weapons? Would the decrease in nuclear weapons spark a conventional arms race? As the number of nuclear targets decreases, would some nuclear states target cities and population centers instead?

Few ethicists have addressed these questions with the necessary degree of nuance and sophistication. Now that nuclear disarmament has been mainstreamed in the policy debate, the ethics of nuclear use and deterrence should be married to an ethic of disarmament.

Now that nuclear disarmament has been mainstreamed in the policy debate, the ethics of nuclear use and deterrence should be married to an ethic of disarmament.

Since the most difficult disarmament dilemmas arise only as the world gets near zero, the United States and other nuclear powers should not be deterred from making significant progress toward reducing nuclear weapons. Major General William Burns, former director of the Arms Control and Disarmament Agency, recently suggested that the United States and other nuclear weapons states could safely reduce their nuclear arsenals to 100 weapons each within a decade. Other expert proposals envision similar levels. Reducing weapons to this minimum would make the world safer and build momentum toward the eventual elimination of nuclear weapons.


Realizing the goal of nuclear abolition will require major changes in regional and global politics. It will require the development of a non-nuclear norm that is at least as strong as the non-use norm that has developed since Hiroshima. Nuclear states have a special responsibility to contribute to the development of that norm, but, as the campaign to ban landmines demonstrated, the role of civil society will also be crucial. Civil society groups must keep reminding their governments that progress on nuclear disarmament has not been commensurate with the dramatic changes that have taken place since the end of the Cold War.

The world is at a critical crossroads. The moral imperative for the United States and other nuclear states is to take the road toward mutual, verifiable nuclear disarmament while working with the international community to close the paths toward further proliferation.

Gerard Powers is director of Catholic peacebuilding studies at the Kroc Institute for International Peace Studies, University of Notre Dame.