On July 6, 2017, the U.S. Conference of Catholic Bishops and the Conference of European Justice and Peace Commissions issued a joint declaration calling upon the international community to “map out a credible, verifiable, and enforceable strategy for the total elimination of nuclear weapons.”

The statement explains its reason for being: the “multipolar” nature of geopolitics today raises a different catalogue of threats than encountered when there were two nuclear superpowers. These threats, the statement says, reach from “terrorism, asymmetrical conflicts, cybersecurity to environmental degradation and poverty” and raise “doubts about the adequacy of nuclear deterrence as an effective response to these challenges.” The undeniable effectiveness of nuclear deterrence rested on a contingent feature of nuclear age geopolitics: a bipolar world where the two leading nuclear superpowers balanced each other, and their allies, against each other in predictable ways. That contingency has given way to the proliferation of variables; each new variable—political multipolarity, novel forms of conflict including terror and cyber-attacks—decreases predictability and makes nuclear disarmament imperative.

Deterrence worked to protect the world from nuclear conflict and even large state-versus-state conflict of the sort seen during two disastrous world wars. The logic of deterrence relied upon the threat of catastrophic destruction. Both the Soviet Union and the United States knew the costs of initiating conflict were too high to bear. If either side started something, both sides would dump as much of their arsenals as possible on each other, to their near-certain devastation.

Post-Cold War “multipolarity” changes that calculation. North Korea, a concern of U.S. foreign policy despite its small size, non-existent economy, and distance from the U.S., reveals the enormous incentive in gaining nuclear capability. Chairman Kim’s dogged, rational pursuit of nuclear weapons insulates his regime from external meddling. The object lesson for other leaders is clear: get nukes before you are changed out by a meddlesome larger power. Non-state actors including the “new” al-Qaeda and ISIS have similar incentives to get their hands on nuclear weapons. Moreover, if they have that incentive, a lucrative market for their sale and distribution emerges. North Korea can make money by selling or trading its nuclear technology to terrorist organizations and other unstable states.

In other words, as Henry Kissinger noted years ago, the demise of the Cold War has created a paradoxical situation: the likelihood of major nuclear conflict between the dominant world powers has evaporated and been replaced by the threat of use of nuclear weapons by smaller states and non-state entities, the latter of which especially escape the logic of deterrence. If, for instance, ISIS detonates a nuclear device in Atlanta, against what location does the U.S. retaliate?

The use of force in politics is oriented towards political goals. One challenge of nuclear weapons has always been conceiving political ends served by their use: can human beings even inhabit territory devastated by nuclear weapons? Nuclear deterrence, however, served the end of political stability, preventing the U.S., USSR, and major states in Europe and Asia from going to war against each other for over half a century. But the very real political goals of some contemporary actors escape the logic of deterrence. The major powers must prevent them from getting nuclear technology: the nuclear powers must recognize they share the goal of non-proliferation and work hard towards its fulfillment. Among the means of securing that goal include working towards nuclear disarmament.

But let’s be clear as well about the process of disarmament: the bishops lament the resources the U.S. spends maintaining and updating its arsenal. Though paradoxical-seeming, arsenal maintenance and replacement is part of effective deterrence, as is resistance to unilateral disarmament. Nuclear disarmament will not be attained by allowing our deterrent response to wither to the point of ineffectiveness. The process of arsenal reduction will be slow and incremental and will feature the odd fact of weapons modernization and maintenance. At the very least, calling for disarmament is pointless without recognizing that disarmament is the end-point of a long and almost certainly herky-jerky process of negotiation and slow, equitable diminishment of nuclear stockpiles.

Joseph E. Capizzi is Professor of Moral Theology at the Catholic University of America. He teaches in the areas of social and political theology, with special interests in issues in peace and war, citizenship, political authority, and Augustinian theology. His latest book is Politics, Justice, and War: Christian Governance and the Ethics of Warfare (Oxford University Press, 2015).

Photo Credit: Second Lt. Chris Davis, 321st Missile Squadron deputy missile combat crew commander, and 1st Lt. Paul Lee, 321st MS missile combat crew commander, simulate key turns of the Minuteman III weapon system during a Simulated Electronic Launch-Minuteman test inside the launch control center at a missile alert facility in the 90th Missile Wing’s missile complex, Neb., April 11, 2017. The 90th MW contributes to the nation’s strategic defense by sustaining and operating 150 Minuteman III ICBMs and the associated launch facilities. A successful SELM test proves the ICBM weapon system’s effectiveness in a safe and secure manner. U.S. Air Force photo by Staff Sgt. Christopher Ruano.