University of Notre Dame
Kroc Institutde for International Peace Studies

Cardinal Roger Mahony

Few challenges are more urgent for Catholic teaching on war and peace than the awesome and unprecedented power of nuclear weapons. In evaluating nuclear deterrence, the U.S. bishops have proposed an “interim ethic” whereby nuclear deterrence could be morally acceptable under three strict conditions:

Sole use. Nuclear deterrence should be limited to deterring the use of nuclear weapons and not expanded to include nuclear-war fighting strategies or using nuclear weapons to deter nonnuclear threats.

Sufficiency. The goal should be to have only enough weapons necessary to deter nuclear use, not enough weapons to achieve nuclear superiority.

Disarmament. Deterrence must be used as a step toward progressive disarmament.

This ethical analysis of deterrence is tightly linked to a nonnuclear ethic—that is, an ethic of nonproliferation and abolition.

In order to counter the idea that nuclear deterrence is an end in itself, Church statements since the end of the Cold War have dramatically shifted in emphasis from the reluctant acknowledgment of the need for a strictly limited deterrent to the need to embrace a nonnuclear ethic.

Archbishop Francis Chullikatt, the Permanent Observer of the Holy See to the United Nations, noted recently that the Church is challenging “the institutionalization of deterrence.” He notes that the doctrine of deterrence has become a permanent, not a temporary, rationale for spending vast sums to maintain and modernize nuclear arsenals for the indefinite future.

The Church abhors any use of nuclear weapons and is convinced that we must move toward a mutual, verifiable global ban on nuclear weapons.

The nuclear powers, according to the archbishop, irresponsibly refuse to enter a process of negotiations aimed at ultimately banning nuclear weapons. The institutionalization of deterrence also reinforces the moral double standard of the nuclear powers, in which some states rely on nuclear weapons while simultaneously denying that right to other states. The institutionalization of deterrence is also a form of theft from the poor, in which billions of dollars continue to be spent on nuclear arsenals while urgent development needs go unmet.

The Church abhors any use of nuclear weapons, finds the nuclear status quo morally unacceptable, and is convinced that the moral imperative is to move carefully but courageously toward a mutual, verifiable global ban on nuclear weapons.

The Church does not reject the need to deter the use of nuclear weapons—that is a moral imperative. But it rejects the view that nuclear deterrence is the only option in the long-term, a permanent component of security in a nuclear age. It is nuclear disarmament, not nuclear deterrence, that is a long-term basis for security.


At the Global Zero Summit in Paris in 2010, Archbishop Edwin O’Brien, then head of the Archdiocese of Military Services, said that as we look ahead, “Every nuclear weapons system and every nuclear weapons policy should be judged by the ultimate goal of protecting human life and dignity and the related goal of ridding the world of these weapons in mutually verifiable ways.”

Steps that could be taken in keeping with that overarching criterion include:

  • ratifying and bringing into force the Comprehensive Test Ban Treaty;
  • reducing our nation’s reliance on nuclear weapons, as the new Nuclear Posture Review begins to do;
  • securing nuclear materials from terrorists as called for at the Nuclear Security Summit;
  • adopting a Fissile Material Cut-Off Treaty to prohibit production of weapons-grade material; and
  • strengthening the International Atomic Energy Agency.

These and other policy measures represent only partial steps on the way to nuclear disarmament.

The United States has a heavy moral burden to bear—and a responsibility to take the lead in nuclear disarmament.

William Perry and other military experts have done groundbreaking work on the complex strategies that must be pursued for a ban on nuclear weapons to become a reality. Similar groundbreaking work must be done by ethicists on the moral issues that arise as the world moves toward nuclear disarmament.

The United States has an especially heavy moral burden to bear. The United States has a responsibility to take the lead in nuclear disarmament and to develop the institutions and practices of cooperative security that will make that more likely and more sustainable.


We must reject the sin of despair that has convinced us that we can never escape the nuclear predicament in which we find ourselves. In its place, we must embrace the virtue of hope. We must not be naïve about the real risks and daunting challenges involved in nuclear disarmament.

We cannot dis-invent nuclear weapons. But, as with biological and chemical weapons, we have a moral obligation and an ability to ban them.

Cardinal Roger Mahony is the Archbishop Emeritus of Los Angeles.