Deterrence in the context of contemporary geo-political turbulence, i.e., “successful deterrence”, is an indispensable key to peace and security (in the absence of common values and norms and interests), but as demonstrated by experiences and lessons learned from the lethal wars in Ukraine and the Middle East, the practice of deterrence, regardless of level and scope, entails an overly demanding exercise of calibration, a dilemma of choice, to avoid unwanted consequences (“unsuccessful deterrence”), notably escalation rather than stabilization. Lessons from “red line” dilemmas in the field can be learned at the highest levels of doctrine and grand strategy. Credibility is the key challenge, especially for a large alliance.

Introduction: the 2024 context

“It has become a cliché to say that this is an unusually dangerous time in world politics. The list of threats to help make the point has become familiar: Russia, persisting with its aggression in Ukraine and menacing all its European neighbours; China, reminding Taiwan that reunification is bound to come, if necessary by force; Iran, close to nuclear capability and stirring up trouble around the Middle East and elsewhere; North Korea, developing its weapons of mass destruction…These countries are by no means the only ones making the world dangerous /a significant understatement, ms/, but they share two features. They are all deeply hostile to the US and its allies and increasingly they work together…. There is a growing concern that in this way they are becoming less a set of separate threats and instead are coalescing into one big threat.” (Lawrence Freedman, June 2, 2024, referring mainly to Philip Zelikow, “The Atrophy of American Statecraft. How to restore capacity for an age of crisis”, Foreign Affairs, Jan/Feb 2024).[1]

This is one way of setting the stage, albeit in a paper focusing mainly on South-East Asian threats and threat perceptions. Another “cliché” would be to refer to the near-unique simultaneousness of a major war in Europe – Russia’s full-scale aggression against Ukraine with no end in sight even after two and a half years of fighting -, another major war in the Middle East the core of which is in and over Gaza between Israel and Hamas but the proliferation risks of which hang over the entire region, notably Iran, winds of potential war blowing also over South-East Asia, with tensions mounting between the US’ allies in the region, Japan, South Korea, Australia and others, reacting and responding to the perceived Chinese (and North Korean, and Russian) threats, and then, obviously, there are the various regional threats, largely multilaterally unattended to these troubled days. Not to mention, incidentally, the added threats related to climate, pandemics, and mass migration.

So, yes, an “unusually dangerous time in world politics”, as rather understated by Freedman. Especially since handling these dangers – from the point of view of “The West” largely depends on a functioning US/US leadership, and since such leadership is currently seen to be jeopardized by destabilizing symptoms of polarization and profound uncertainties in the November 2024 presidential election perspective, the most consequential of the unique series of elections globally during 2024.

In all this/these, the main immediate dangers clearly, and geo-politically, lie in the combination of the risk of the Ukraine war escalating into an open and direct armed conflict between NATO and the aggressor Russia (increasingly explicitly supported by China and “understood” by The Global South) and, on other hand, the Middle East war spreading throughout the entire region and then amalgamating with Russia’s war, if so probably with the Iranian (or Iranian-Israeli) factor serving as the bridge. As tension rises, and with it a gradual decrease in the relevance and survivability of remaining formats for cross-boundary dialogue, community of value and interest further reduces options for peace and peaceful settlement of disputes, in a vicious circle.

This leaves us, for now, with a first statement: the less world peace and stability can rely on a certain minimum of a community/communality of interest and/or values, the more world peace and stability – and mechanisms for a non-violent settlement of disputes – depend on functioning deterrence. Hence the focus is today’s discourse on deterrence, deterrence generally and nuclear deterrence specifically, for acute want of alternatives, any and all discussants realizing that we – the international community – have found ourselves in a new, unknown and unchartered, territory, by any historical comparison (Post WW2, post-cold war, any other): much more multipolar and much less multilateral, the rise of China as a major[2] nuclear power, other products of nuclear proliferation, nuclear deterrence having failed to deter a major war in Europe, globalization, digitalization, hybrid warfare, closure of arms control talks, increased tension, escalation risks, etc, etc. Consequently, a lot of legitimate focus internationally on functioning (“successful”) deterrence – nuclear and/or conventional, strategic and/or operational – as an indispensable instrument for peace and stability in an unruly world.

Hence, while deterrence, whether nuclear or conventional, is key in contemporary doctrines and strategies, a closer look exhibits not only a highly complex academic/strategic discourse – “deterrence and defense” as in current NATO lingo, or “punitive” deterrence versus deterrence “by denial” and other concepts, but also and especially a defining policy dilemma which will be discussed hereunder. At issue here is also the distinction between deterrence as a strategy – the effort to dissuade the adversary from going ahead with perceived aggressive intentions – and “strategic ambiguity” (as a strategy). At a high level of generalization, the basic question to be asked here concerns what is more efficient in making an adversary abstain from perceived aggressive intentions, clarity of deterrence through specific threats, or quite the opposite, keeping the adversary mystified as to probable reactions on the part of the opponent. (It should be noted here the difference – functionally – between “strategic ambiguity” and a key tool in the toolbox of diplomacy, “constructive ambiguity”.)

In reality, the two, deterrence and strategic ambiguity, are more often than not complementary rather than opposite, sometimes in such a way that “successful deterrence” (theoretically) represents “Plan A” while keeping the adversary ignorant and guessing concerning “Plan B”, should the intended deterrence not be successful. The interplay is further complicated by the reality that deterrence gaming is normally mutual, in a process of action-reaction, both sides struggling with their dilemma of deterrence. And – worse – both sides likely to perceive of the other side as “offensive” rather than “defensive”.

By way of conclusion of this introduction, noting that in the international strategic discourse some are claiming that the present is the most dangerous period we (in the West, et al) have experienced since WW2 while other make the end of the cold war their line of reference, with little else (left) as incentive and means for preventing outbreak of large-scale, lethal/kinetic war in the competition between states and other actors for leverage, other than “successful” deterrence, this necessary focus – in largely unknown territory – at the same time necessitates realization that deterrence/strategic ambiguity represents a risky game and a policy dilemma; what if aimed at (increased) deterrence instead leads to escalation, and how to formulate – and communicate – a relevant Plan B should the initial deterrence (your “red lines”) not be respected by the other side?

The central concept here is credibility. And the central problem is that of measuring; I am sure to know, the hard way, the reality of failure, but how do I know if and when a policy of deterrence has in fact succeeded? How do I avoid the adversary being tempted to test the reliability of credibility by various means, in a scale from a big strike in order to dare a fait accompli to a series of small, “salami tactical” steps? And how do I take into account the factor of asymmetry, the fact that asymmetrical relations and qualities require weighing different kinds of means in the deterrence equation, on both sides – in fact a “SWOT”-analysis: (assessing “strengths, weaknesses, opportunities and threats” in the famous acronym).

The role and function of deterrence in this context; the dilemma of deterrence

Now, in view of the context outline above, let us move on to what official NATO has to say about all this. Relevant texts are there in abundance, e.g. the final communiqués from the summits in Madrid and Vilnius which in so many words for instance elaborate why it is of essence consistently to talk about “deterrence and defense” as key twin concepts (since deterrence “only” could be seen to imply speculation in the feasibility of a “tripwire” mechanism only, i.e., weak deterrence). But sufficient here to refer as a source to a NATO standard briefing/PowerPoint, presented by Jim Stokes, Director of Nuclear Policy, Defence Policy and Planning Division, NATO International Staff at a Stockholm Pugwash seminar on May 20, 2024.

In this, the “Nuclear Deterrence Equation” is presented as

Credible Capabilities” plus “Political Resolve” plus “Effective Communications” being “perceived by opponent” leading the opponent to a Judgement not to act, the outcome of which is “Successful Deterrence”.

This definition, or anatomy, of “successful deterrence” thus has several prerequisites, theoretically since in reality it is almost by definition near-impossible to judge if and when absence of aggression depends, directly or indirectly, on “successful deterrence”. In the list of prerequisites, as pointed out earlier, credibility is a sine qua non and necessary ingredient. Without credibility, communicated to and perceived by the opponent, deterrence cannot (by definition) be “successful” or effective. And credibility has to be based on both relevant capabilities – relevant to the strategic aim and level of the deterrence policy – and a demonstrated readiness to use these capabilities as pledged, should the opponent choose not to comply sufficiently, or at all. This in turn depends, for effect, on the deterring side’s ability to reach out and communicate, convincingly, to the receiving end the political resolve of the combined forces being part of the deterrence policy. Failure to achieve the intended element and amount of deterrence will, thus, depend on insufficient capabilities held forth and perhaps demonstrated in exercises, or an insufficiently convincing display of political resolve and unity of purpose (as in an alliance like NATO).

But an “unsuccessful deterrence” may also be due to a wrongly calculated balance between deterrence (and defense) and perceived risks of escalation, largely depending on the contextual question of whether the deterring side is perceived to be on the “offensive” or rather on the “defensive”. So it is very much a question of mutual perceptions, like in a game of chess, trying to anticipate the next move (and the move after) of the opponent, and my resulting options. Clearly no rocket science, although rockets may come in handy as pawns in the chess game.

The purpose of this paper is to illustrate from the current scenes in Ukraine and in the Middle East the main thesis of the paper: that in a geo-political context of steadily deteriorating relations, in and over Europe and globally, the factor of deterrence is critical key, but – in a context of largely unknown territory – that the exercise of deterrence (deterrence and defense as specified by NATO, and occasionally an intricate combination of deterrence and “strategic ambiguity”) is more often than not a problematic strategic dilemma, at all levels of armaments and geographic scope. It is maintained that concrete experiences from current areas of open, kinetic conflict offer lessons to a deepened understanding of similar, largely untested dilemmas at the strategic, nuclear level in this new situation.

It needs, then, to be specified what is meant here by labelling deterrence – including the exercise of exchanging “red lines” as the means of operationalizing deterrence in terms closer to the battlefield or area of conflict – a strategic dilemma, bearing in mind that the aim of deterrence is avoidance of open warfare while sticking to stated strategic objectives, be they (perceived as) offensive or defensive – although deterrence is typically conceived of in a defensive strategic perspective. However, there is also the variety in which an offensive aggressor seeks to deter expected or feared responses to acts of aggression planned or threatened, i.e., preemptive deterrence of sorts. The Ukraine case provides ample examples of these action-reaction dynamics.

Deterrence is calculation of risk and a balancing act, in different ways and at different levels. You are hoping/seeking to make the adversary abstain from aggression while avoiding that the net result is instead escalation in a continued action-reaction process. Deterrence means threatening retaliation, but for full, relevant credibility such retaliatory response needs to comply with Jim Stokes other criteria; merely maximizing the element or criterion of available capabilities, perhaps as demonstrated in exercises, will hardly bring about “successful deterrence”, strictly defined, unless there are convincing manifestations of political resolve.

This critical balancing act, seeking to handle the dilemma of risking “failed” deterrence and unwanted consequences would seem, so it is claimed here, to apply to the whole spectrum of relevance to deterrence, from the wider, comprehensive and general level of nuclear deterrence (cf the development in US/NATO thinking from “massive retaliation” to “flexible response” and ensuing variations of these) to the operational specifics of parties to an armed conflict exchanging “red lines” in a sequence of action-reaction and changing and inter-changeable red lines. The purpose of this paper is to illustrate the latter with examples from Ukraine and the Middle East. And to draw some tentative lessons from these to the wider geo-political area.

The Ukraine war: ever-changing “red lines” and unresolved questions regarding “successful deterrence”

It was long believed that nuclear deterrence and the principle of MAD (mutually assured destruction) and the ensuing strategic stability as established in the later Cold War period and largely maintained in ensuing post-cold war period would render a major war in Europe virtually impossible. That was until February 24, 2022, when, contrary to this, Vladimir Putin launched his full-scale war against neighboring Ukraine.

A first moment in a sequence, or duel, of deterrence here is then the troubling fact that Putin decided to defy Western deterrence, both the general nuclear deterrent (that obviously lacked credibility) and the specifics of pledged (“devastating”) sanctions combined with a host of military steps in support of Ukraine and particularly exposed eastern-most member states (that obviously lacked efficiency), by attacking Ukraine. Western deterrence was unsuccessful in preventing Russia’s aggression. The measures then pledged came then to serve as punishment for Russia’s refusal to comply, and as attempted deterrence against continued Russian aggression, whether vertically (escalation) or horizontally (expansion).

As from this point, any account of the ensuing sequence of deterrence events has a accept the element of uncertainty following the fact that Putin’s war in and against Ukraine is an unfinished story, rendering assessments in terms of “successful” or “unsuccessful” at least difficult. The exception, perhaps, is that one can say, as a matter of fact, that the build-up of Western capabilities not least in the border areas of eastern-most member countries – and the strategic emphasis on “deterrence and defense” – with a view to communicating to Russia (and Belarus) that “not an inch” of NATO territory would be left undefended, and undeterred. Clearly, so far, this policy of deterrence has been “successful”. But other than this case, a host of issues remain unclear, in an unfinished chain of action-reaction, partial successes and tentative failures, all indicative of the difficulties in handling the dilemma of deterrence in a context of conflictual and worsening geo-political relations.

But there is, and remains, a problematic link between the “success”, so far, in NATO’s deterrence of Russian aggression against Alliance member states, now as enlarged by inclusion of Sweden and Finland, and the host of unresolved issues pertaining to the “deterrence duel” between NATO and Russia over Ukraine, and remaining risks of both vertical and horizontal escalation, here with the distinction between offensive and defensive less clear in the perception of the two sides during the course of the war. Russian “red lines”, real, aspired for and/or perceived, have been first identified and then adapted to and then ignored over time by Joe Biden and his NATO colleagues, an exercise in temporary “self-deterrence”, pending assessments of Russian reactions, essentially out of fear of escalation, ultimately the Third World War.

The latest step in the process, as we have seen, is a recent decision by dominant NATO leaders to abandon the hitherto restriction concerning Ukrainian use of Western-supplied weapons against targets on Russian soil, and a declared inclination on the part of several NATO leaders to seriously consider crossing another delicate “red line”, allowing NATO personnel to operate for training purposes on Ukrainian soil – both as a response to recent Russian advances on the Northern and Eastern front lines. Hints, for Russian deterrence against these escalatory moves, at nuclear threats from the Kremlin have proved insufficient to deter NATO from crossing these “red lines”.

And this is where the Ukraine war stands at the time of writing, with profound uncertainty as to where and with what outcome the war will end, and apparently with a firm determination on both sides that only a more or less total victory is the war aim worth fighting for – and threats of both horizontal and vertical escalation still, and increasingly, looming. At the time of writing, it is unclear what difference the planned “peace conference” in Switzerland in mid-June may make in this regard. But for NATO, clearly, the lesson learned so far is that quite a lot more military (and other) aid in support of Kiev’s struggle for sovereignty and survival is needed if Ukraine is to stand a chance against mounting Russian military power, even at the clear and present risk that such necessary increase in aid – both amounts and restriction removal – will lead to (unwanted) direct military conflict between NATO and Putin’s Russia and perhaps to deepened military cooperation between Russia and China (and North Korea, and Iran?).

To deal with this big, even huge, dilemma facing the uncertainties of the next few months and years requires Alliance leadership for vital cohesion and co-ordination, and here of course the uncertainties and worries pertaining to the US presidential elections are also looming. It will, thus, be greatly interesting to observe how NATO will deal with these issues in the July Washington birthday summit. What concrete lessons have been learned from two and a half years of war in Ukraine, notably as regards the relevance and effectiveness of nuclear deterrence in a “proxy war” between the Alliance and Russia, with partners.

The Middle East war: “successful” and “unsuccessful” deterrence

October 7,  2023, is a date of profound stature in the Israeli history of existential threat and survival, with the unique brutality of Hamas striking southern Israel with deadly force. And the ensuing Israeli retaliatory onslaught on Gaza, causing unique suffering among affected Palestinian civilians, has contributed to disrupting pre-existing efforts at stabilization of the entire Middle East region and given rise to a huge challenge to US diplomacy as the would-be guarantor of peace in the region while remaining a, or the, close ally of Israel, ever since 1948.

Standing by Israel in this deep crisis has cost the Biden administration considerably, also in the presidential election perspective, and as the Gaza war has been protracted over an incredible almost 9 months (at the time of writing), with toxic issues pertaining to the enormous humanitarian Palestinian suffering together with Israel’s problematic war objectives and the hostages and ceasefire conditions eluding resolution, the threat of conflict proliferation has remained clear and present. Thus, military clashes between Hezbollah in Lebanon and Israeli IDF across the border in Israel’s north have continued unabated, while Houthis in Yemen have continued to bombard shipping in the globally crucial Red Sea, and pro-Iranian and pro-Palestinian militias in Iraq and Syria have continued to threaten US military presence in these countries, all these with explicit reference to the Gaza crisis.

Of course, as is well known, this acute crisis has a very complex contextual background, one component of which is the tense Israeli-Iranian relationship over deterrence, Israel´s deterrence power as a de facto nuclear power and Iran´s deterrence power as a state broadly suspected of aspiring for nuclear power status and a state enhancing regional leverage by using proxies in neighboring countries. As a means of enhancing stability in the long fragile region, of supporting Israel and countering the perceived Iranian threat, the aim of US diplomacy has in recent years been to use carrots rather than sticks in promotion of Golf and other Islamic/Arabic states recognizing Israel, in spite of the lingering, unresolved Palestinian issue. This policy (“Abraham Accords”) was also a means for the US to let go of some of its long-standing and costly commitments in the region, in favor of other priorities.

The US leadership, having quickly declared its total and unconditional support for Israel and its PM Benjamin Netanyahu, sought to prevent the feared horizontal escalation of the crisis and the conflict by assembling a massive deterrent force of two aircraft carrier groups with hundreds of war planes on board off the Middle East coast of the Mediterranean, then also, together initially (and traditionally) with the UK, a naval force patrolling the Red Sea, with a view to deterring and responding to Houthi threats against global shipping.

Judging whether these steps represent “successful deterrence” on the part of the US and its varied partners, is of course very difficult in the context of an ongoing conflict, especially as regards the Red Sea and the action-reaction “duel” still ongoing there, but of particular relevance here is the continuation on other theatres in the region.

For even if in the relationship between close allies the word “deterrence” may seem, even be, inappropriate, it is apparent that US deterrence in this case also applied to Israel, at least indirectly: US deterrence power sought to deter the ally Israel from both a massive preemptive strike against Hezbollah in southern Lebanon (as planned by Israel/IDF in the early stages of the post October 7 crisis) and from escalatory, provocative attacks against Iranian interests and proxies in neighboring Syria and Iraq. The former was and remains “successful”, in the sense that Israeli IDF has so far abstained from the feared massive attack against Hezbollah – even though the protracted military cross-border incidents have necessitated costly civilian evacuations on both sides, and considerable casualties, even if limited in comparison with Gaza.

But the massive deterrence build-up did not deter pro-Iranian (and pro-Palestinian) proxy groups from repeatedly raiding US military targets in the region. It took specific military action by US forces to achieve a significant pause, apparently an effective act of pro-active deterrence since an effective (“successful”), Iran-accepted, pause was indeed, achieved, for the time being.

But then it was Israel’s turn to cross an Iranian “red line”, the missile/drone attacks killing several high-ranking Iranian IRGC officials in Damascus, making the leadership in Teheran pledge retaliation, leaving it open as to when and how and hence uncertain in terms of a spiral of deterrence and retaliation. The situation was comparable to that some years ago when the US under Trump carried out the assassination of ICRG general Suleimani at Baghdad’s airport, raising the question of to what extent the Iranian response would necessitate a US response in kind, and thus release a dangerous spiral. In the end, de-escalation was facilitated by a demonstrably limited response.

This time, the Iranians chose to respond rather massively, with hundreds of drones, ballistic missiles and cruise missiles directed directly at Israeli targets, but offering warning time sufficient for US and allies to prepare a very effective air defense response, in fact so effective as to make it possible in the end for the US to persuade the Israeli leadership that in this case of (albeit massively supported) Israel air defense success, a new round of Israeli retaliation – with a view to “restoring deterrence” (a frequently used term these days of strategic uncertainty) – was really not  necessary, not worth the price (of further escalation).

But with the Gaza war continuing and a resolution – or at least ceasefire and release of hostages – still eluding massive efforts (at the time of writing), the jury is still out when it comes to whether and to what extent hitherto attempts at deterrence (on the part of the US and other actors) can be said to have been “successful”. One tentative answer could perhaps be that, yes, deterrence has been relatively successful, so far, in the sense that the Gaza war and related atrocities have indeed been prevented from spreading into a major regional war with global implications. And the Iran-Israel conflict has, so far, not taken on nuclear dimensions, as far as we know. But at the same time, the real non-proliferation implications of the current Middle East crisis obviously remain unknown, perhaps one of several “unknown unknowns”.

Nor do we have a clear picture of how US (and Israeli) policies of deterrence against Iran and the Iran-led “Axis of resistance” will, or might, in the longer term tend to provoke or accelerate the formation of a more global “axis of resistance”, combining Russian, Chinese, Iranian and North Korean strategic interests.

Concluding reflections

The less there are factors of common values and compatible interest, and universally respected institutional expressions of such factors, to provide for global and regional stability and the existence of mechanisms for peaceful settlement of unavoidable disputes, the more deterrence (hopefully “successful deterrence”) comes to the fore as a necessary tool for stability and peace, varieties in which depend on whether the world order is essentially multipolar, bipolar or unipolar. Hence, in the current situation of unstable multipolarity, whereas functioning (“successful”) deterrence may well be seen as the best, or only, alternative to open warfare, deterrence in practice is unavoidably a balancing act between risks of failure, including risks of escalation instead being the net outcome. Deterrence in practice, or “immediate deterrence”, therefore involves a difficult dilemma: how to maximize (and communicate) deterrent effect while minimizing counter-productivity risks – that further escalation instead becomes the unintended consequence and/or that non-compliance by the adversary (“bluff calling”) compels you to deliver as pledged and/or invites the adversary to continuously test your resolve (and hence the credibility of your deterrence ambition) by repeated “salami tactical” steps, further straining your resolve and hence your credibility. If tested, the art of credible deterrence, especially on the part of an alliance deemed by the opponent to be notoriously potentially fragile, is essential but critically complicated, and risky.

The question of whether in some situations “strategic ambiguity” as a policy is more effective as deterrence – making the adversary abstain from aggression out of fear of the unknown as regards what to expect from the other side – than explicitly threatening specific, dire consequences of non-compliance is open to further scrutiny, based on experience of practices in the contemporary context.

But it is clear that deterrence in general, whether extended/nuclear or conventional, general or operationally specific, “successful” or “unsuccessful”, cannot be understood sufficiently in a dynamic, mobile (hence escalatory) geo-political context, unless related to the concept pairs of action-reaction, offensive-defensive and symmetry-asymmetry, together with understanding of the mutual nature of deterrence, and the power of perceptions in a context of mutual uncertainty. Careful calibration is needed, for “successful deterrence”, of a lot of things that can go wrong. The current cases exemplifying this suffer from being ongoing, leaving us with the jury still being out as regards estimates of degrees of success.

What all this means with regard to the formulation of nuclear deterrence doctrines – based on the experiences of recent years’ struggle with the consequences of and lessons from the co-existence of two separate but potentially linked major wars, undeterred by the arsenals and doctrines of existing nuclear powers, will be greatly interesting to observe, as from the Washington Summit in mid-July, this time with Sweden participating as a full member, with full co-ownership of the outcome.

The author is ambassador, holds a PhD and is a fellow of RSAWS.
This was presented at the Alva Myrdal Centerannual conference 18th June


[1] This is a draft of a larger study, part of the Sv-A-R- project within the Royal Swedish Academy of War Sciences, to be subsequently developed in substance, detail and appropriate documentation. It is party based on findings accrued in the Academy’s former SES project. Apologies for the absence here on references from an overwhelmingly rich international library of relevant reference materiel. And particular thanks for useful input to colleagues Lars-Erik Lundin, Lars Wedin, Ian Anthony, Krister Andrén and Karl Sörenson.
[2] In more stable times in world affairs, reference was more commonly made in the strategic literature to security policy as essentially a balancing act between deterrence and “beroligelse”, a Norwegian term standing for reassurance (of the adversary), diplomacy, confidence-building, and the like, i.e., attempts to communicate to the adversary your basically peaceful, defensive and non-aggressive purposes, while resisting aggression by the adversary. While this doctrine element is not entirely absent in today’s Alliance strategic language, its relative disappearance but from the highest levels of political rhetoric, is indicative of a perception of a serious and steadily worsening security situation, globally and regionally.