The debate about how far the West should go in supporting Ukraine against Russia’s invasion is a serious one, with weighty consequences. Reasonable people in good faith can disagree about what precisely is at stake for third parties, beyond caring altruistically for Ukraine’s survival. Disagreeing over whether and how far our core security interests are threatened, we can therefore disagree about how much risk to take. This judgement matters, because it determines how far we should put limits on the provision of Western arms and intelligence, and the conditions of their use. The question is too serious, and too weighty, for one glib line that some “maximalists” like to repeat — namely, that in providing a large arms, intelligence and financial aid programme to Ukraine yet not going further the West is practising “self-deterrence” in the face of Vladimir Putin’s aggression.

“Self-deterrence” is an unserious concept — at least when deployed as an expansive description of refusing to act more assertively — used as a poor substitute for substantive argument. It is a quickfire way to claim that the West should dismiss and ignore any possibility that Russia — the very aggressor the same maximalists claim presents a first-order threat to our interests — might ramp up its aggression further and more directly.

The notion of “self-deterrence” was originally a late Cold War-era term. It initially referred to one party’s reluctance to use nuclear weapons for moral or normative reasons; a concern that retains specific contemporary relevance. For example, concern that British deterrent posture might lack credibility against non-existential (but still deadly) attacks after the retirement of the last UK tactical nuclear weapons — given the grave humanitarian costs of resorting to strategic nuclear retaliation — motivated HM Government to articulate a “sub-strategic” role for Trident warheads that can be detonated in a lower state of yield (a role that they have subsequently stopped discussing, although the capability remains). In today’s Ukraine debate, however, it has become a cruder device, to suggest those in favour of limiting efforts for fear of escalation are driven irrationally by implausible fears.

Since all deterrence entails an attempt to influence the mind of others, there cannot be deterrence without the “self”

If deterrence is the process of dissuading another party not to take a certain action, and doing so with the threat of denial or punishment, then as a very simple point, that process always and necessarily involves the target making a conscious decision whether to be deterred. To accuse the U.S. and or its allies of being “self-deterred” is to imply that there also exists an alternative, more virtuous form of deterrence that somehow works automatically, unmediated by the deterree. There does not. Since all deterrence entails an attempt to influence the mind of others, there cannot be deterrence without the “self”. So “self-deterrence” and “deterrence” is a distinction without a difference.

Similarly, those who traffic in this rhetoric like to rebrand the act of choosing to be deterred in the face of escalation dangers in starkly moralist terms. It is, they allege, succumbing to “blackmail.” This suggests that any choice of restraint in order to survive, on behalf of millions of fellow citizens, is weak and immoral. And it assumes that restraining oneself over one thing in one place, even if it is peripheral, is the equivalent of wholesale backdown and capitulation. The whole point of alliances like NATO, or the Warsaw Pact, is that they present counter-blackmail threats, not over everything everywhere, but over the protection of core interests somewhere, like a group of aligned states within the North Atlantic Area. When the Soviets limped out of Afghanistan in 1989, Washington and its allies rightly did not infer that it was open season to strike them across the Fulda Gap.

The stakes here are high; too high for dismissive rhetoric. In 1962, as the U.S. confronted the Soviet Union over Cuba, President John F. Kennedy wisely overruled the demands of some of his advisors that he go beyond an intermediate measure of blockade, and bomb the missile sites. He feared that launching direct attacks would force Moscow’s hand and trigger a general war. He was more right than he knew: we now know that Red Army commanders, stationed in Cuba, were authorised to use nuclear cruise missiles to destroy the U.S. naval base at Guantanamo. Who comes out of this episode better, the cool-headed Kennedy, steering a course between confrontation and tacit concession? Or the war hawks warning about Munich and weakness, who only took seriously the danger of under-reaction? Can we recognise their equivalents today?

Not only is the notion of “self-deterrence” tautological. Not only is its implied distinction with other kinds of deterrence baseless. It also reflects an overconfident assumption that Putin and Russia have no “red lines” that they would enforce, and would never dare to attack the West directly or use the ultimate weapon, even in extremis — despite our own confidence that we would do exactly that under grave enough pressures. Deterrence is a difficult matter precisely because it is striven for amidst uncertainty. It involves subjective judgements, made without full information, and against adversaries (potential or actual) whose own intentions are unclear, and who may also change their minds. A little prudential caution is due.

Yet, regarding the most consequential question of all, namely whether the war could go nuclear and whether the West should take such risks into account, hawks like Phillips O’Brien and Eliot Cohen (the latter of whom has used the self-deterrence line) offer swaggering certainty:

The same expert analytic community that erred early in the war continues to dominate much of the public and governmental discourse … Some of them still warn of Russian escalation, up to and including the use of nuclear weapons, even as one Russian red line after another has faded to pink and vanished.

Notice the structure, the sheer dismissive recklessness, of this argument. Russia has a large nuclear arsenal, but because Putin’s earlier escalatory threats against the West, his “red lines,” proved false, all of them are bound to be, even if the war turns badly against Moscow. Because some people cautioned against escalation risks earlier in the war that — thanks to careful escalation control — have not yet manifested, they are bound to be wrong now. Because the West has nuclear weapons too, it can choose not to be deterred from ever more direct intervention, faithful that Russia will still choose to be deterred. Shall we rest the survival of our countries on these non-sequiturs? What if they are wrong?

Fears of escalation are fears about real things, informed by history and, when carefully worked through, by reason

Russia has deadly capabilities, ones that might be tempting to use if or when the West were to start attacking directly its other conventional forces. It demonstrably cares about its position vis-à-vis Ukraine. And, as hawks themselves remind us frequently, its regime is murderous and immoral. The chances of it resorting to the unthinkable if it fears defeat — a defeat that threatens its regime or country — may still be low. But they are not zero. And they may well be higher than vanishingly low. After all, the most plausible scenario for nuclear use, launching strikes against battlefield forces in order to shock an oncoming enemy into backing off, was NATO doctrine in the late Cold War. If we assessed that such a posture could be a source of security and a route to political victory — and were confident our forces would carry such a doctrine through — it would be imprudent to assume that the Kremlin could never reach the same conclusion.

Fears of escalation are fears about real things, informed by history and, when carefully worked through, by reason. Those fears are morally serious, since they involve the welfare of those our governments are supposed to protect. There is sense, still, in worrying about the prospect of nuclear war as we make hard judgements about which risks to take. And there’s honour in it.