Deterrence: what it can (and cannot) do

Deterrence is making a comeback. Perceived by many as a mere relic of the Cold War, the Russia-Ukraine crisis has hastened its resurrection. However, the debate over the past months as to how best to deter Russia reveals that 20 years of neglect have taken their toll. Much of what was once considered basic knowledge on deterrence appears to have evaporated. What, then, is deterrence? What can it achieve – and what can it not?

Deterrence is the threat of force in order to discourage an opponent from taking an unwelcome action. This can be achieved through the threat of retaliation (deterrence by punishment) or by denying the opponent’s war aims (deterrence by denial). This simple definition often leads to the conclusion that all it takes to deter is to put enough force on display. As long as both sides act “rationally”, i.e. according to a cost-benefit calculus, and if none of them is suicidal, their military potentials will keep each other in check.

If only it were so easy. History abounds with examples of deterrence failing despite a balance of forces, and even cases in which the weaker side attacked the stronger. In some cases, the weaker side banked on the element of surprise. The military leadership of Imperial Japan, for example, was fully aware of US military superiority. But if a surprise attack on the Pearl Harbor naval base would destroy a major part of the US Pacific Fleet while paralysing Washington politically, Japan might stand a chance of prevailing. In 1973 Syria and Egypt attacked the militarily superior Israel – not because they hoped to win, but because they wanted to re-establish the political clout they had lost after Israel had defeated them in the 1967 Six-Day-War. Israel had not seen the attack coming: why would two militarily inferior countries even think of attacking an opponent that was certain to emerge victorious? This self-assuredness led Israel to ignore the many warning signals about a pending attack. As a result, the rapidly advancing armies of Egypt and Syria were initially much more successful than expected. Military superiority had not ensured deterrence.

HMS Andromeda and SS Canberra outside Port Stanley on 16 June 1982, in the Falklands

Another important example for the pitfalls of deterrence is provided by the 1982 Falklands War. Argentina, which contests the United Kingdom’s authority over the islands in the South Atlantic, knew only too well about the superiority of the British armed forces. However, over the course of several decades the UK had gradually been reducing its military protection for the islands. Thus, while London kept emphasising that the Falklands were British, the military Junta in Buenos Aires became convinced that such statements were mere lip service. When the Junta faced a domestic crisis that threatened its rule, it tried to generate support by stirring patriotic feelings and occupied the islands. Deterrence had failed because the United Kingdom had ignored an important factor. Striking a tough pose while at the same time reducing the means to make good on it undermines one of deterrence’s most important ingredients: credibility. The story did not end there, however. Much to Argentina’s surprise, the British Navy sailed to the South Atlantic and re-conquered the islands. General Galtieri, the Chief of Argentina’s military Junta, later admitted that he never believed that a European country would be ready to pay such a high price for a few insignificant islands so far away. Argentina, too, had miscalculated.

But could Galtieri and his fellow countrymen not have guessed that a proud nation like the United Kingdom would not stand idly by as part of her overseas territory was being occupied by another power? Should one not have known that remaining passive would have spelled the end for any British government? The answer: yes, in normal times Argentina may well have pondered such scenarios. However, in a crisis humans tend to think along a different kind of logic. Indeed, many studies about human behaviour demonstrate that people who fear to lose something valuable are ready to take greater risks than those who hope to make a gain. In the context of the Falklands War, this means that for the Junta, which was under siege politically, occupying the “Malvinas” was not about a gain, but rather about avoiding losing power. This made them take risks they otherwise would not have dared to take. Rationality – a precondition for a stable deterrence system – had evaporated.

Looking at Russian domestic politics today, the lessons of 1982 are worth reconsidering: stirring nationalism in order to generate political support may lead one to military adventurism which can be self-defeating.

Cuban missile crisis in 1962

All these cases demonstrate that deterrence is not just about military balances, but also about interests. If the opponent’s interest in achieving a certain objective is higher than one’s own, deterrence may fail. A classic example is the Cuban missile crisis of 1962. When it became clear that Washington was ready to defend its core security interests, the Soviet Union withdrew the missiles it had started to deploy in Cuba. Another example is the Vietnam War. Although the United States was militarily far superior, it ultimately had to withdraw because the North Vietnamese and the Vietcong were willing to make much greater sacrifices to achieve their goals than the US was willing to make in support of South Vietnam. This asymmetric set of interests not only makes deterrence fail, it also makes big powers lose small wars.

But what about nuclear deterrence? Should the fear of the enormous destructive power of such weapons not be enough to virtually guarantee deterrence? The answer to this question is the same as to the “conventional” examples cited above: even in the nuclear domain, deterrence depends on the interests that one seeks to protect. If a nation’s existence is at stake, the use of nuclear weapons is credible. Accordingly, deterrence between nuclear weapons states is considered to be relatively “stable”. By contrast, extending one’s national nuclear deterrence to allies is much more complicated. As British Defence Minister Denis Healey put it in the 1960s, one only needed five per cent credibility to deter the Russians, but 95 per cent to reassure the Europeans. Despite this “Healey Theorem”, however, extended nuclear deterrence has become a central pillar of international order. This is not only the case for NATO, but also for the Asia-Pacific region, where Japan, South Korea and Australia are under the US “nuclear umbrella”.

It is moot to speculate whether the United States would indeed be willing to risk nuclear escalation in order to protect an Ally. What counts is the political signal that Washington views the security of its Allies as a fundamental national security interest. However, such a message will only be convincing if the US is militarily present in those regions that is claims to defend. This ensures that in a conflict Washington will be involved from the start. Without such a presence, neither Allies nor opponents would perceive such a nuclear commitment as credible.

What conclusions can be drawn for Western security policy?

First, a renewed debate about deterrence must be cautious not to oversell that concept. The temptation to do just that is already visible. For example, some peace researchers have argued that the tactical nuclear weapons stationed in various NATO countries could be withdrawn, since they failed to deter Russia’s aggression against Ukraine. If this logic were sound, one would also have to abolish all national militaries and even NATO itself. For no army and no alliance has deterred Russia from annexing Crimea and destabilising Eastern Ukraine. A more realistic analysis of the Ukraine situation will find that this is less a case of deterrence but of geography and interests. Russia is ready to prevent Ukraine’s Western integration even with military means, while the West is not willing to risk a military escalation on behalf of a country that does not belong to NATO. Put differently, the example of Ukraine is ill-suited to prove or falsify deterrence. If anything, it demonstrates that a country that is politically and militarily weak is easy prey for a powerful neighbour.

US troops in Lithuania

Second, given Europe’s current security situation, NATO’s foremost task is to ensure the military protection of its geographically most exposed members. The Alliance’s new “Readiness Action Plan” (RAP) foresees increasing the readiness-level of NATO’s reaction forces, and holding increasingly complex exercises in Central and Eastern Europe. The RAP includes a “spearhead” force capable of deploying within a matter of days, the establishment of a multinational NATO command and control and reception facilities on the territories of several eastern Allies, and the updating of defence plans. Although NATO’s emphasis remains on the rapid projection of reinforcements rather than on the permanent stationing of substantial combat forces in Central and Eastern Europe, the RAP reflects the reaffirmation of a principle that for some time had been receiving short shrift: in order to communicate deterrence through credible defence one needs to match one’s rhetoric with the appropriate military posture.

Third, the nuclear dimension of deterrence will have to be re-visited as well. Although not in the public limelight, Russia is also sending nuclear signals to the West: by stepping up nuclear exercises, by having Russian bombers flying closer to allied borders, and by boasting the development of new nuclear weapons. In autumn 2014, Russia’s Deputy Prime Minister Rogozin even promised that Russia’s military modernisation would contain a “nuclear surprise” for the country’s potential adversaries. All this reveals that Russia’s thinking, both politically and militarily, is far more “nuclearised” than most Western observers believed. The West does not need to mirror-image Russia’s approach. However, it will have to ask itself whether the post-Cold War tendency to largely ignore nuclear deterrence and to look at nuclear weapons mainly in the context of disarmament is still in line with today’s security landscape. Given Russia’s behaviour, as well as the risk of new nuclear powers emerging in the Middle East and parts of Asia, the West will have to re-learn some lost principles of deterrence.

Fourth, deterrence must also include non-military aspects. In Ukraine, Russia has provided a textbook example of hybrid warfare: the rapid concentration of regular forces at Ukraine’s border, the employment of unmarked special forces in Crimea, support for separatists in Eastern Ukraine, an increase in the gas price and a massive propaganda campaign that sought to obscure the events on the ground. It is arguable whether this kind of warfare, which aims to create ambiguity that could make NATO’s decision-taking difficult, can be deterred merely by the threat of force. Deterring hybrid war will also require other means, such as increased resilience of cyber networks, diversification of energy supplies, and strategic communications that can rapidly correct false information spread by an opponent. Rather than punish an aggressor with military reprisals, “deterrence-by-resilience” seeks to dissuade him by demonstrating the futility of his approach.

Fifth, the United States remains the linchpin of Western deterrence. This is not just due to their tremendous military power, but also their political will to act as a guarantor of global order. Should the US lose this will – or lose its ability to convey it – others would soon test the various “red lines” drawn by Washington. Despite a debate about domestic priorities, the US remains keenly aware of this fact. At the start of the Crimea crisis, the US quickly enhanced its military presence in Central and Eastern Europe, backing up its promises of assistance with concrete military hardware.

Nothing could better illustrate the enormous significance of the US presence than a photo of an American armoured vehicle on a highway in Lithuania. Many Lithuanians sent the photo to each other on their mobile phones. The text underneath the picture said more about deterrence than a thousand textbooks: “Awesome! They could have come 70 years earlier though ...”

the Author

Michael Rühle is the Head of NATO’s Energy Security section and is a former speechwriter to the NATO Secretary General.