Vladimir Putin’s recent announcement to place his nation’s nuclear deterrent forces on a state of heightened alert invites those of us in the free world—and surely the United States—to revisit the just war assumptions that served as a deterrence during the Cold War. Contrary to public statements by President Joe Biden’s press secretary, we should not merely view Putin’s announcement as part of a “pattern” of him “manufacturing threats” that simply “don’t exist.” As was the case in the Cold War, those threats do in fact exist, even when they are not realized. The issue is whether those threats can be deterred.

In addition, the related commentary in the West that attempts to analyze Putin’s “aggressive statements” through the prism of “mental stability” and “rationality” at this point is irrelevant and wholly misguided. This sort of speculation is anchored in a way of thinking that misconstrues the totalitarian mindset. Putin’s failure to achieve an early “lightning strike” success should not induce in Western thinking a foolish optimism; the Russian tyrant will simply double down and intensify his attacks.

The wisdom of just war thinking—a mindset that constitutes a 2,000-year-long conversation in the broader Western cultural tradition—assesses issues of human dignity, justice, law and order, and the common good in moral and political rather than psychological terms. It refuses to divorce political action from the use of power or force. In a fallen world, in which both good and evil exist and regimes are capable of doing unspeakable horror to human beings and societies, the tendency toward evil must be restrained. It has always been so.

Sadly, we can see the divorce of political action and force among both conservatives and progressives, even when their reasons differ. As recent history demonstrates, the political-diplomatic approach of “all measures short of war” has led to disaster for nations and societies. Why? Because the modern assumption that only peaceful (i.e., non-coercive) measures can achieve good purposes is false. The use of power or force is the very essence of politics, as ethicist Paul Ramsey argued during the height of the Cold War. Power and politics cannot be separated, and a common good—whether in domestic life (think taxation or criminal justice) or international affairs—is impossible without measured force.

Political responsibility for a nation like the US is not merely humanitarian aid, diplomacy, or a matter of “sanctions,” as important as these are. Based on moral law, it requires the presence of justice and order, which are interlocking and inseparable. To illustrate, the United Nations at most can only engage in “peacekeeping” (to be distinguished, of course, from Putin’s claim of “peacekeeping” in Ukraine); it possesses no ability, actively speaking, to protect the common good (think the “killing fields” of Southeast Asia in the 1970s and ’80s, genocide in Rwanda and central Africa since the mid-’90s, and ongoing deprivation of basic human rights worldwide). In the twenty-first century, we must be careful not to “spiritualize” or idealize political action. Responsible political action will often—when not always—require coercive force to preserve the common good. St. Augustine was correct: we go to war in order to achieve an enduring peace. That peace is usually a process—a process involving the unfortunate but morally requisite resort to war or coercive force.

The just war doctrine—which is perhaps more accurately denominated a “justified war” doctrine—justifies coercive intervention on the basis of moral-prudential considerations. It asks what justice (as opposed to injustice) and order (as opposed to disorder) require, and it asks what will build the international common good. In the words of Ramsey, “No authority on earth can withdraw… rescue from dereliction and oppression all whom it is possible to rescue.” These are difficult words for a postmodern era—and for members of NATO, which since 1989 have “cooperated” with totalitarian regimes rather than seeking to deter them. Deterrence, alas, has fallen out of fashion, and both Ukraine and Taiwan (in the near future) illustrate this tragic reality.

Communists and totalitarians of our age have no theory of “unjust conduct”; all class struggle, after all, is “just.” Nothing is forbidden, as Putin and Chinese dictator Xi Jinping announced at the beginning of the recently concluded Olympic Games. In stark contrast, the just war tradition announces, “Yes, there are some things that are forbidden. All things are not to be tolerated.” This moral commitment is expressed in the tradition’s key conditions that undergird (a) whether or not to intervene (ius ad bellum)—the centrality of legitimate political authority, the justness of one’s cause, and the importance of right intention—and (b) how to execute that intervention (ius in bello), the essence of which is proportionality to the threat and discriminate means of intervention. To believe that some things are forbidden and not to be tolerated is to affirm the justice of deterrence, which aims to prevent gross injustice.

Three generations ago, the US and its allies used their influence wisely and authoritatively to end World War II and the encroachment of totalitarianism that had engulfed Europe and Asia. Despite the Soviet threat, which had emerged three decades earlier, and the Chinese totalitarian threat, which arose shortly after the war’s end, the Cold War danger was contained—deterred—until 1989. Both Russian and Chinese totalitarianism reemerged since then because, at least partly, the West disavowed the reality and necessity of deterrence; we have been embracing cooperation and appeasement for the last thirty years.

Nuclear capabilities, of course, lay at the heart of Cold War tensions. But what induced considerable debate in the decades of the Cold War and what today impedes meaningful dialogue and discussion of the importance of military deterrence is the matter of weapons and strategies that, in fact, have the capacity to deter. At the center of that discussion is the fear that some weapons are inherently evil, weapons whose existence simply cannot be justified for any reason and application.

Whether for religious or secular reasons, the West has largely imbibed the pacifistic view—which at best relies on diplomacy, sanctions, and, at worst, retreats from the world—that confrontation and conflict are illicit. The broadly held assumption is that nuclear weaponry, given its vast destructive capacity and effect, cannot be contained or used for just purposes. This view, which makes the world unsafe for all, needs to be challenged.

During the Cold War, Ramsey and William V. O’Brien were among the few to articulate a counter-force nuclear strategy, based on just war moral reasoning. Rogue nations, they argued, have shown that they will pursue nuclear armament, as North Korea and Iran at present demonstrate. Just war thinking affirms the need for deterrence—tactical and responding deterrence as opposed to “first-strike” strategy—as well as limits and restraint. A nuclear threat does not exist until an aggressor creates it. Deterrence that is proportionate and discriminate—that is, tactical and measured as well as aimed at military targets—establishes a powerful incentive not to cross a line. Just war thinking as applied to policy communicates to the aggressor what is forbidden, what will not be tolerated. Deterrence, properly viewed, targets the enemy’s forces, based on just war’s counter-force intent, and it does so proportionately to the threat. Counter-force warfare has as its aim a just peace, not mutual destruction of societies. Intention, not the amount of destruction, dictates what in the end is the just use of force.

Just war moral reasoning has no intrinsic bias against technology or strategic weapons. Not nuclear capability per se but how that capability is used constitutes the burden of just war thinking. Moreover, as just war theorist Darrell Cole has argued, there is a sliding scale, as it were, of varying nuclear weapons—some are high-precision and low-effect in nature while others are low-precision and high-effect. A just use of some high-precision nuclear weapons, given the priority in just war strategy of precision and discrimination, can be morally justified and might be necessary. By contrast, Russia’s attacks on Ukraine thus far have involved imprecise bombing, resulting in the murder of thousands of Ukrainians. At the same time, just war reasoning refuses to recognize the legitimacy of “first-strike” nuclear tactics; a morally justified nuclear strategy is, rather, a response. It is a “victory-denying” tactical strike that prevents a greater evil. In its nature, just war thinking acknowledges the threat and is discriminate and proportionate in its response to that threat. The same, of course, guides “criminal justice” in the domestic context. Law-enforcement officials and police do not throw up their hands in despair or deny the reality of deterrence because criminals employ destructive means that far exceed civil society’s ability to protect and prevent. To permit such would be both unjust and inhumane.

In a fallen world, deterrence, punishment, and retribution are necessary. That necessity does not stop simply because some humans, possessing dictatorial power, are abnormally evil. To engage in deterrence is not some “dirty hands” lesser evil that should be purged from “civil society” as we know it. It is not immoral or unjust to deter an aggressor from perpetrating social-political evil; rather, it is an affirmation of the dignity of all people—with rights and freedoms that inhere in that dignity.

As Russia creates a bloodbath in Ukraine, Western leaders—and especially President Biden—must not be content merely with a so-called “unity.” A “humanitarian horror” is in process, and the goal must be to stop Putin from conquest. What is a moral deterrent? It is the strategically guided application of coercive force that is proportionate to the threat, guided, limited, and discriminating. It is not an end in itself but serves the common good of people and nations when and where gross social-political evil is manifest.

Coexistence with communist and totalitarian regimes remains a present reality. “Peaceful coexistence” with totalitarian police-states is a fantasy, for there the “rule of law” simply does not exist. Nor do human dignity, human rights, and basic freedoms. Totalitarianism’s ideology of the state prevents relatively free societies from “peaceful coexistence,” since as an imperium it seeks world domination. In such a regime, war is ongoing domestically, eliminating any “enemies of the state,” and a natural outgrowth internationally of its imperial priorities. Because of its commitment to maximum security, a nuclear arsenal is important to its survival.

Given the horror and bloodshed of the Ukrainian situation, some around the world and in the West will surely call for Ukraine’s surrender. But this would be immoral and unjust. Therefore, the West needs to be prepared for all possible and necessary scenarios related to war.

Russia and China are nuclear imperialist powers and must be engaged at that level. Deterrence is responsible statecraft applied to military strategy. As history reminds us, nuclear deterrence can be guided by just war commitments, which aim both to hinder an aggressive enemy and prevent an initial nuclear strike.