2 July 2022

Resetting NATO’s Defense and Deterrence: The Sword and the Shield Redux

Sean Monaghan


Deterrence has been central to the North Atlantic Treaty Organization’s (NATO) strategic concepts since the beginning. The first such concept, “Strategic Concept for the Defense of the North Atlantic Area,” known as DC 6/1 and approved in December 1949, declared as its main objective: “To coordinate, in time of peace, our military and economic strength with a view to creating a powerful deterrent to any nation or group of nations threatening the peace, independence and stability of the North Atlantic family of nations.”2

The primary mechanism through which NATO sought to deter Soviet aggression was deterrence by punishment through the threat of American atomic weapons.3 Yet NATO’s focus on atomic weapons was not just about deterrence—it also strengthened its ability to defend itself if deterrence failed.4 NATO’s early emphasis on nuclear weapons stemmed from its assessment of the vast numerical superiority of Soviet forces in comparison to its own. As MC 14, the detailed strategic guidance that accompanied the first strategic concept, stated: “special emphasis must be laid on the necessity for developing methods to compensate for numerical inferiority.”5 MC 14 also assumed any war with the Soviet Union would be total in nature, which justified the strategic concept’s reliance on nuclear deterrence.6

NATO’s first strategic concept also introduced a second pillar of deterrence: deterrence by denial through positioning adequate forces to defend allied territory against invasion. In other words: if you want peace, prepare for war. This approach complemented the threat of nuclear punishment but would require NATO to develop sizable military forces. An early estimate in 1950 called for at least 90 land divisions, over 7,000 fighter aircraft, and over 2,000 warships of various sizes.7 The focus of this defensive effort was on the European “couverture facing east of the North Atlantic Treaty area.”8

In other words, NATO’s denial strategy was one of forward defense designed to “arrest the enemy advance as far to the East as possible.”9 It was also strengthened through active opposition to peacetime aggression “by all measures short of war.”10 Rather than denying territory, these efforts were aimed at denying Soviet freedom of action to target the political function and cohesion of NATO nations through political warfare.11


The substance of NATO’s second strategic concept mirrored the first.12 It retained and built upon the two pillars of deterrence outlined in its predecessor: deterrence by punishment (through strategic bombing and conventional military power) and by denial (through forward defense and measures short of war). The Korean War had also impressed on NATO the need to press forward with its defense plans to counter further potential Soviet (or Soviet-sponsored) aggression—not least to avoid divided Germany meeting the same fate.13

As a result, this concept strengthened the denial pillar through what it referred to as a “forward strategy” for the defense of Europe “to hold the enemy as far to the east in Germany as is feasible, using all offensive and defensive means available to deny or limit his freedom of action to the maximum extent.”14 The detailed strategic guidance aimed at “having the maximum forces available at the very outset or at least ready to come into action in the first few weeks.”15 This policy raised the level of ambition for NATO’s deterrence by denial strategy, aiming to convince Soviet decisionmakers that any attempt to take territory would incur severe costs. This element of NATO’s deterrent strategy would take on an even larger role in future strategic concepts as allies developed the forces required to implement it.
The Sword and the Shield: NATO’s Third Strategic Concept (1957)

NATO’s third strategic concept reiterated the centrality of deterrence to NATO’s mission: “Our chief objective is to prevent war by creating an effective deterrent to aggression.”16 This concept was the first to refer to nuclear weapons by name and the first to advocate using them for what became known as “massive retaliation”—including the possibility of their first use in response to conventional Soviet aggression.17

It built upon both of NATO’s established pillars of deterrence: the forward strategy of denial and the threat of punishment by strategic bombing. Taken together, the two pillars became known as NATO’s “shield” (forward-deployed forces) and “sword” (the U.S. strategic bomber force).18 The concept, therefore, required two kinds of forces: “There are powerful nuclear retaliatory forces, composed chiefly of long-range strategic air striking forces mainly under national command. There are also the land, sea, and air shield forces which by their deployment and by their defensive capabilities demonstrate that aggression, no matter what the form, will be effectively opposed.”19


The formal adoption of NATO’s “massive retaliation” doctrine in 1957 built on the deterrence by punishment pillar established in 1949. This evolution occurred for both economic and strategic reasons. First, NATO needed to counter much larger conventional Soviet forces—and their growing nuclear arsenal—with more sustainable levels of defense spending that would not threaten economic growth.20 Following the United States’ “New Look” defense policy—which considered “nuclear weapons to be as available for use as other munitions”—NATO also developed a so-called “New Approach” to integrate nuclear weapons into its strategy amid allies’ concerns over the expense of meeting their own force goals.21

The strategic necessity of massive retaliation stemmed from “the advent of nuclear weapons systems [which] has drastically changed the conditions of modern war.”22 NATO concluded, that however, a general war came about, whether initiated by the Soviets or via inadvertent escalation due to miscalculation, the threat of Soviet total war and “the rapid overrunning of Europe” would require NATO to “first ensure the ability to carry out an instant and devastating nuclear counter-offensive by all available means.”23

The Shield

The development of NATO’s shield forces complemented its nuclear sword as an insurance policy against limited war and other hostilities. As U.S. general Lauris Norstad, then supreme allied commander Europe, put it in 1958: “For if our line is not defended throughout, the enemy might trump up a pretext for crossing it.”24 The basic task of NATO’s shield forces was to deter Soviet aggression by denying their freedom of action, defending “as far forward as possible in order to maintain the integrity of the NATO area”—including Scandinavia.25

Shield forces also formed part of NATO’s integrated nuclear deterrent and early warning and alert system.26 They also reinforced the doctrine of massive retaliation. As General Norstad explained: “if our line is being held in reasonable strength, and if the enemy knows this beyond doubt, then any inclination on his part to cross the line makes him face the terrible decision of detonating World War III, with a sure prospect of his own annihilation. The defensive forces deployed on our eastern boundary thus become an essential part of the deterrent.”27

Yet NATO’s shield forces were not seen as merely a “tripwire” for massive retaliation.28 As Malcolm Hoag of RAND argued in Foreign Affairs at the time: “why maintain land forces to serve as a ‘trip-wire’ to trigger retaliatory air blows?”29 Moreover, the shield forces’ vulnerability to nuclear attack may render them pointless.30 Yet Hoag, and many others, would also argue against relying on massive retaliation, which was “a frightful risk to run.”31 These debates led to NATO’s fourth strategic concept.

Flexible Response: NATO’s Fourth Strategic Concept (1968)

The main idea behind NATO’s fourth concept was a shift away from relying on “massive retaliation” toward a policy known as “flexible response” that would provide NATO with a graduated response to a non-nuclear crisis, rather than the blunt instrument of massive retaliation.32 This approach added a “flexibility which will prevent the potential aggressor from predicting with confidence NATO’s specific response to aggression and which will lead him to conclude that an unacceptable degree of risk would be involved regardless of the nature of his attack.”33

This change in policy came about toward the end of the 1950s for two main reasons. The first was the growing nuclear parity between the Soviet Union and the United States.34 Now that the United States could be targeted by Soviet nuclear weapons, many Europeans feared this undermined the credibility of NATO’s American nuclear sword and argued NATO should give more weight to non-nuclear deterrence.

A second reason for NATO to take non-nuclear options more seriously was provided by the crises in Berlin (1958–62) and Cuba (1962), which led U.S. secretary of defense Robert McNamara to conclude: “our great nuclear superiority for general war does not solve all our problems of deterring and dealing with less than allout direct assault.”35 Relying on massive retaliation undermined deterrence because it required NATO to decide whether to initiate general nuclear war, a step that Soviet leaders knew the West would be unwilling to take in all but the most extreme circumstances.36 This left a deterrence gap that McNamara expected the Soviets to exploit further: “The Berlin crisis exemplifies a type of threat that we should expect to face elsewhere in the NATO area. In such a crisis the provocation, while severe, does not immediately require or justify our most violent reaction.”37

McNamara argued “a stronger non-nuclear posture would confer large political benefits on the Alliance.”38 NATO’s shield would force the Soviets to think twice, not its sword. He claimed this was the case in Berlin and Cuba, where “non-nuclear forces were our sword, our nuclear forces were our shield.”39 In the years that followed, this reasoning was reflected in the alliance’s fourth strategic concept, which aimed to deter aggression using three types of flexible response:“Direct defence,” which “rests upon physically preventing the enemy from taking what he wants. A capability for direct defence in any contingency is a deterrent to that contingency”;

“Deliberate escalation,” through non-nuclear force or selective nuclear strikes; and

“General nuclear response,” or massive retaliation.40

To bolster the credibility of NATO shield forces, the fourth concept emphasized “rapid augmentation of its forward posture” through “appropriate echeloning in depth in suitable tactical locations,” logistic support, tactical mobility, supplementing local forces with those of allies, and a fully trained, equipped, and ready NATO reserve force.41

Nearly two decades of planning and refinement had resulted in a balanced strategic concept founded on two pillars of deterrence: the threat of punishment through overwhelming nuclear response to Soviet invasion or nuclear use—“massive retaliation” using NATO’s “sword”—combined with the denial of Soviet freedom of action short of war through a forward-deployed “shield” force that NATO could rapidly reinforce. This approach to deterrence underpinned NATO’s strategy for the next two decades and played a crucial role in ending the Cold War. As Hans Binnendijk points out, “the effect was to greatly lessen NATO’s vulnerability to surprise attack and political intimidation, to reduce undue reliance on nuclear escalation, and to raise legitimate doubts about the Soviet Union’s ability to prevail over NATO in a conventional war.”42

A Broad Approach to Security: NATO’s Three Post–Cold War Strategic Concepts

The new era in European security also triggered a new phase of thinking about NATO’s strategic concept. While the four Cold War strategic concepts were mostly concerned with the balance between nuclear and conventional deterrence—the sword and the shield—the three concepts adopted since the end of the Cold War moved away from deterrence as the sine qua non of NATO’s purpose and strategy.43 They focused instead on balancing a wider range of core tasks, including dialogue, cooperation, consultation, collective defense, crisis management, conflict prevention, partnerships, and cooperative security.44 This new approach was captured in the 1991 concept under the rubric: “A Broad Approach To Security.”45

Although the threat of “Soviet military capability and build-up potential, including its nuclear dimension” remained present, “the Allies concerned agreed to move away, where appropriate, from the concept of forward defence towards a reduced forward presence, and to modify the principle of flexible response to reflect a reduced reliance on nuclear weapons.”46 In other words, the strategy that had served NATO since 1957 had now changed. The “forward defense” that formed NATO’s shield and the doctrine of “massive retaliation” and “flexible response” that made up NATO’s sword were now all but gone—or at least reduced in scope and ambition to the point where they were substantively different.

Instead, alongside a much reduced “forward presence” among eastern allies, NATO would come to rely on an approach that had surfaced in its fourth strategic concept in 1967: deterrence by reinforcement.47 As the new concept made clear, “the maintenance of a comprehensive in-place linear defensive posture in the central region will no longer be required.”48 Instead, “capabilities for timely reinforcement and resupply both within Europe and from North America will be of critical importance.”49

NATO’s post–Cold War strategic concepts also placed a new emphasis on the ability to project power out of area through expeditionary operations.50 Diego Ruiz Palmer described this shift: “during the Cold War, NATO’s guiding operational paradigm was Forward Defense, from northern Norway, across West Germany, to eastern Turkey; in the post–Cold War era . . . the operational paradigm became NATO’s capacity to conduct expeditionary operations of varying purpose and scale.”51

This added up to a substantial change in NATO’s strategy. During the Cold War, this had required NATO to arm itself, under the rubric of the sword and the shield, with the most powerful set of forces the world had ever seen. In contrast, after the Cold War, NATO’s strategy was to disarm itself, hoping to hang up the sword and the shield for good, replacing them with a “balanced mix of forces” to implement the new broad approach to security.52 As the new concept declared: “The Allies seek, through arms control and disarmament, to enhance security and stability at the lowest possible level of forces consistent with the requirements of defence.”53

NATO’s sixth and seventh strategic concepts, in 1999 and 2010, took this transformation further, aiming for “an optimum balance” between high readiness crisis response forces and those capable of gearing up for “the worst case — but very remote — scenario of large scale operations for collective defence.”54 These two concepts also doubled down on deterrence by reinforcement and refocused on the Article 10 provision for enlargement, adding significant new political and military power to its ranks to strengthen deterrence.55
The Return of Deterrence: The Post Post–Cold War Era

“We, the Heads of State and Government of the member countries of the North Atlantic Alliance, have gathered in Wales at a pivotal moment in Euro-Atlantic security. Russia's aggressive actions against Ukraine have fundamentally challenged our vision of a Europe whole, free, and at peace.” – Wales Summit Declaration, September 5, 201456

The opening words of the Wales Summit declaration captured the moment, in 2014, when reality overtook NATO’s post–Cold War strategic concepts. Russia’s annexation of Crimea and sponsored conflict in the Donbas region of eastern Ukraine fatally undermined the approach to deterrence NATO had pursued to maintain stability in Europe since 1991.57

NATO’s initial reaction to the events of 2014 was to strengthen its strategy of deterrence by reinforcement combined with forward presence, before adding “an enhanced forward presence in Estonia, Latvia, Lithuania and Poland” of four multinational battlegroups at the 2016 Warsaw summit.58 This “tripwire” posture would be underpinned by the ability to “rapidly reinforce any Ally that comes under threat, when needed, to counter all contingencies.”59 It would also be complemented by a new commitment to treat “cyber” and “hybrid” attacks as armed attacks under Article 5.60 This policy extended deterrence by denial through a whole-of-society approach to “total defense,” expanding NATO’s shield beyond the military domain to that of civil society and even individual citizens.61

Although it may have been a fragile equilibrium, NATO’s post-2014 adaptations to its defense and deterrence posture seemed to be holding the strategic balance in Europe intact. Russia’s full-scale invasion of Ukraine on February 24, 2022, shattered this illusion. Even though Russia’s armed attacks were not made against a NATO member, the ramifications of Russia’s brutal attempt at armed conquest were clear: Europe was not whole, free, and at peace, and NATO was now in Russia’s sights.62

In hindsight, the “same but different” approach to NATO’s post–Cold War strategic concepts did not survive reality. The authors of the 1991 strategic concept drew two parallel conclusions: “The first is that the new environment does not change the purpose or the security functions of the Alliance, but rather underlines their enduring validity. The second, on the other hand, is that the changed environment offers new opportunities for the Alliance to frame its strategy within a broad approach to security.”63

Although presented as harmonious, these two assertions turned out to be contradictory. Thanks to Russia’s evolution under the Putin regime, the undeniable validity of NATO’s purpose—that of, first and foremost, deterring armed aggression—prevented it from realizing any new opportunities to move beyond its raison d’etre. For a while, it seemed like this might not be the case, as the alliance played crucial roles in Bosnia, Kosovo, and Afghanistan. Yet it has since become clear NATO did not have the capacity to both maintain sufficient deterrent forces while managing out-of-area crises and develop a broader approach to security.

In reality, the “same but different” approach required a trade-off between the forces and posture required to deter Russia and the “balanced mix of forces” required to broaden NATO’s approach to security.64 Reductions in defense investment by allies while Russia increased funding to modernize its forces compounded the fundamental problem: the strategic balance shifted in favor of Russia to the point where NATO’s basic assumptions were no longer valid, and a reset would be required to maintain deterrence.65

In the long run, the “new environment” hailed in 1991 was not so new after all.66 Like the Soviet Union before it, the Russian Federation continued to define itself in opposition to NATO, both in zero-sum security terms and with respect to the liberal democratic values of its members.67 Whether this was inherent to Russia’s geopolitical situation or down to the decisions of the Putin regime did not matter to NATO—either way the result was a reversion to the Cold War mean and the requirement to open yet another chapter in its approach to defense and deterrence.

Reductions in defense investment by allies while Russia increased funding to modernize its forces compounded the fundamental problem: the strategic balance shifted in favor of Russia to the point where NATO’s basic assumptions were no longer valid, and a reset would be required to maintain deterrence.

Resetting NATO: The Sword and the Shield Redux

“What we are looking for from NATO in this next phase is long-term planning for how it will contain Russia post Ukraine and provide resilience and reassurance to countries that cannot do that on their own. That could be permanent basing or it could be rapid readiness—being able to deploy quickly, instead of being stuck in a big base in one place. That is all up for development, which I think is incredibly important.” – Ben Wallace MP, UK Defence Secretary, May 19, 202268

NATO’s defense and deterrence reset will begin in Madrid when its leaders open the next chapter of their alliance with its eighth strategic concept. Like its predecessors, the concept will set the vision and basic principles that will guide NATO through this testing time.69 But the devil will be in the detail. As Britain’s defense secretary Ben Wallace stated recently, the finer points of NATO’s new strategy, such as whether it will rely on deterrence by reinforcement or through permanently forward-based forces, will require development by NATO’s military planners in the weeks and months after Madrid. What can they learn from the history of NATO’s strategic concepts?Plan against Russian “Maximum Intentions”

The guidance that accompanied NATO’s first strategic concept advised that for defense planning purposes: “Precise Soviet intentions are not known and cannot be predicted with reliable accuracy. For military planning purposes, however, it is essential to consider maximum intentions and capabilities.”70 This is sound advice considering the inherent uncertainty in estimating adversary intentions and plans.71 It is also best practice for military planning.72

Moreover, in light of Russia’s current actions, NATO’s 1956 assessment of Soviet intentions and their implications are strikingly resonant today. Beyond the following highlights, the assessment is worth reading in full:73

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