NATO’s Response to Russian A2/AD in the Baltic States: Going Beyond Conventional?

Anti-access/area denial (A2/AD) has turned very recently into a buzzword to define Russian strategy to limit, disrupt or even interdict NATO forces to reinforce the Baltic states in the case of an escalation between the alliance and Russia. This article puts in context how these discussions have re-emerged since 2014 and how Russia has developed a comprehensive defense system that effectively give the impression of impenetrable ‘bubbles’. Yet, NATO has to cope with a not-so-new threat, being caught between two extremes: on the one hand, being serious and credible – maintaining its superior technological military edge and show-casing it by deploying troops and materials in contested areas, and on the other hand, being a defensive alliance, not giving any credit to the Russians by creating a dangerous spiral. This paper argues that it is time to develop a truly comprehensive counter-A2AD strategy, which would take several aspects: maintaining and expanding the reassurance measures (in the air, on the seas and on the ground), improve our doctrines to think big again (by recreating divisions and corps as maneuver units) and consider the need to be seen as a credible deterrent. These military aspects would be complemented by political and diplomatic considerations to ensure possible retaliatory measures, if Russia would further destabilize its neighborhood through an aggressive policy. What is at stake is NATO’s being not just a resilient and adaptive organization facing todays’s complex challenges, but its core ability to maintain, 70 years after its birth, the very notion of collective defense in which all the allies trust.

-Citius (faster) means being more agile in every compartment and at every level, from decisionmaking to the sheer ability to move forces throughout allied countries, and thus reduce the risk of being caught unprepared. -Altius (higher) raises the stakes by recovering high-end capabilities that have been either eroded or left aside as well as being willing to make escalation cheaper and create a sentiment of vulnerability by forcing Russia to react to activities in other areas of contact with NATO countries. -Fortius (stronger) is self-explanatory and calls for an increased volume of forces, where readiness is key.

A Buzzword to Define a Historical Reality?
If ' anti-access and area denial' as a concept traces back to the 1990s in the US strategic community, its reality is as old as warfare. Denying any possible adversary its freedom of movement on the battlefield or, more comprehensively, the ability to even approach one's disputed territory can be illustrated by numerous examples: One thinks of either building barriers -great walls and fortification lines -or striking far ahead in anticipation -cutting lines of communication or raiding the bases and harbors from where an invasion fleet would set sail, for instance. According to Milan Vego's definition, 'the success of any major operation or campaign depends on the free movement of one's forces in the theater. Without the ability to conduct largescale movements on land, at sea, and in the air, operational warfare is essentially an empty concept ' (2009: III-7). To better highlight the complexity of the defending strategy, the choice was made by the Center for Strategic and Budgetary Assessments (CSBA) to create a concept that would distinguish the enemy actions that inhibit military movement into a theater of operations (anti-access) from the activities that seek to deny freedom of action within areas under the enemy's control (area denial). Geographic delimitations and echelons of war therefore apply, even if linked together for the sake of clarity (Krepinevich, Watts, & Work 2003). 2 Henceforth, A2/AD would be a holistic defensive strategy that would focus on all possible 'warfighting strategies', preventing an opponent from ' operating military forces near, into, or within a contested region' (Tangredi 2013: 1). 3 Traditionally, these strategies are pursued by states or regimes that fear an invasion -mainly from the sea. In the past, traditional measures would be to build coastal defenses, fortify harbors and develop some indepth defenses that would avoid any deep penetration of one's territory (Gatchel 1996). Countering projection from the sea benefited from the technological developments that were spurred by the Great War: The Turks were able to close the Dardanelles Strait in 1915 by combining coastal fortifications and heavily mined waters, forcing the Anglo-French force to shift to an ill-fated ground invasion. By the same token, Germany implemented this very principle in the North and Baltic Seas during World War I by developing a stronghold in Heligoland, combined with a lethal, but relatively inexpensive fleet (torpedo boats and submarines) that kept the British fleet out of German waters and turned the North Sea into a 'naval no man's land'. World War II opened new perspectives on the evolution of A2/AD as a concept: The defense of the British Isles in 1940 relied on the implementation of a radar network to identify and target incoming aircrafts, while the Royal Navy patrolled at sea and ground forces built trenches and land fortifications. The Germans would follow a different approach from Dieppe (1942) to the landings in Italy (1943) andNormandy (1943), never being able to repulse the attacking force. Eventually, the Cold War and the development of a new category of weapons systems changed the nature of A2/AD: The Soviet Union introduced innovations that extended the range and lethality of existing arsenal, while developing new capacities that increased the envelope over which anti-access was possible.
Interestingly, the concept once again aroused interest in the 1990s. At that time, the Chinese People's Liberation Army (PLA) and Navy carefully analyzed and scrutinized the US-led Operation Desert Storm, where the rapid and unchallenged deployment of massive forces into the theater of operations was the first condition of success. Followed by the 1995-1996 crises in the Strait of Taiwan where China was unable to oppose the deployment of a US carrier group, the Chinese military concluded that in the event of a conflict with the US, they had to disrupt or neutralize the American military deployment in their region. The emphasis was placed on the technologies that enabled the development of 'weapon systems of greater reach, immediacy, and accuracy' (Alcazar 2012: 44). Moreover, in order to increase the layers and lethality of its military capabilities, the Chinese PLA has extended well beyond the traditional domains of air, sea and land, with reports of possible attacks ' on cyber and space targets [which] threaten to disrupt or even completely deny multiple enablers of power projection, including but not limited to satellite communications and Global Positioning System (GPS) based navigation systems' (McCarthy 2010: 4).
The 'Chinese A2/AD model' does not solely rely on missiles and state-of-the-art weaponry to limit or prevent the deployment of US forces. It entails a form of diplomatic pressure on regional actors that are compelled to choose between ' a future with a belligerent neighborhood threat and a United States whose interest might wane', which might lead current allies to appease the A2/AD rival and limit or prohibit air and naval access or overflight (Alcazar 2012: 46). In this sense, every A2/AD strategy undercuts the US-preferred union of power and force projection by preempting or precluding force options: It ' can circumvent America's traditional military strengths, thereby blunting U.S. military power' (Brookings Institution 2012: 9).

Russian A2/AD: Strategy and Means
In Europe, A2/AD only became a matter of interest after Russia's illegal seizure of Crimea. At first, most of the allies were concerned with the new forms of warfare waged by Russia, which were labeled 'hybrid', as they aligned both conventional and unconventional tactics. 4 Whilst the expert community was still debating the scope and efficiency of the Russian military modernization under Putin, results were at least tangible and pointed out Russia's return as a major power with a military that was better prepared, better trained, better equipped and more capable than only a decade ago. It is a truism to say that the Russia of 2018 has nothing to do with the Soviet Union, both in terms of strength, allies and resources. In terms of comparison, NATO is Goliath and Russia David, which also underlines that measuring the balance between NATO and Russia has never been so complicated since the end of the Cold War. NATO has grown, but its largest military commitment ever, in Afghanistan, may have degraded rather than reinforced the bonds between its militaries. Interoperability and readiness are still an issue (see e.g. Schmitt 2018). On the other hand, assessing Russian unit strength and the real capabilities of the Russian forces -with the exception of elite forces -remains a challenge (Marten 2017: 18). The strategic imbalance between the two also explains why Russia has deliberately chosen to pursue two parallel, yet connected courses of action: Its 'hybrid' tactics maintain such uncertainty that it could theoretically avoid a full-scale reaction from its adversary, thus avoiding a frontal reaction to Russian crawls in its immediate neighborhood. At the same time, Russia has more so than ever before developed significant conventional capabilities sought to deny Western forces permanent access to what would become contested areas, using old strengths in air defense and guided missiles that Russia inherited from the Soviet Union.
Russian A2/AD is one visible military response to protecting its territory. A2/AD capabilities are concentrated in several 'bastions' where overlapping systems provide comprehensive defense against air and naval attacks, and from which Russian air, missile and naval forces can project power into the surrounding countries and sea and airspace. As such, the build-up of Russian A2/AD bastions can be seen both as a response and a threat to regional security. 5 These bastions contribute to a strategy that builds on three key elements: -Depth of maneuver: Through mobility, launchers can move quickly and avoid being targeted and destroyed whilst being able to strike far ahead. -Strategy of interior lines: Russia has recently developed a strategy of coordinating and synchronizing very closely all types of military units, for instance during the latest series of Zapad exercises (see e.g. Petraitis 2018). -Multi-dimensional capabilities: subsurface, surface, air, space and cyber and a strong ISR.
Being at the same time permanent and very mobile, the potential A2/AD 'bubbles' are therefore not only present in the Western part of Russia where NATO territory and former Soviet territory overlap (the Baltic countries and the Kaliningrad exclave). Russia could also create isolated zones in the Arctic/Barents Sea, the Black Sea, the eastern part of the Mediterranean and the Pacific -in conjunction with China, its ally. 6 This A2/AD strategy relies on the limited means that Russia can afford, and they are chosen because they outmatch NATO forces when and where it counts (Zapfe & Haas 2016). Russian A2/AD primarily builds on multi-layered air defense systems, namely the S-300 and S-400 families. The latter leapfrogs in the domain of air defense weapons, as it can theoretically ' engage all types of aerial targets'up to 36 simultaneously 'including aircraft, unmanned aerial vehicles (UAV), and ballistic and cruise missiles within the range of 400km, at an altitude of up to 30km' (Army Technology n.d.: para. 6). One of the most iconic is the Iskander series (9K720 or SS-26 Stone), a short-range ballistic missile that potentially violates the 1987 Intermediate Nuclear Forces Treaty. Possibly nuclear-tipped, the Iskander has been fielded in Kaliningrad to respond to the deployment of US Aegis Ashore systems (Hutchison 2018). Beyond the advertisement, what is certain is the connectivity between all these systems, from anti-ship to anti-air missiles; it creates a bubble because it forms a system of systems, supported by upgraded delivery platforms, from submarines to new surface ships and fifth-generation aircrafts (PAK FA or Sukhoi T-50) and retrofitted Tu-22M bombers. Furthermore, this system seems to be affordable, meaning that Russia exports it to allies and clients, which could result in the multiplication of A2/AD 'bubbles' around the world. 7 Let us return to a scenario where the Baltic countries is a prey. The recent Russian involvements in Ukraine, the Balkans and Syria -all with different modalities and purposes -highlight the different courses of action that serve the Kremlin's strategic ambitions. During a first phase, a galaxy of various (predominantly nonmilitary) actors would shape the environment in a fashion that could take years. Ranging from diplomatic to economic pressure, using energy security as a lever, and instrumentalizing Russian-speaking minorities, this would create the conditions for a possible intervention. After an incident that could be staged by whatever entity, let us imagine that the situation quickly deteriorates. In this case, speed would be a key requirement in order to freeze the situation. For Russia, there would be three possible courses of action: First, ' anti-access' activities would be used to create de facto almost impenetrable bubbles and thus limit NATO reinforcements through increased military activities on the seas, under the seas, in the air and in cyberspace. Deployment of particular capabilities (especially air defenses), the set-up of a no-fly zone, combined with diplomatic pressure on the neighboring countries -up to nuclear threat -would be part of the expected panel of actions. More kinetic ' area denial' actions could potentially happen at the tactical/operational level in the case of direct confrontation between NATO/national and Russian forces. Without exploring the risk of rapid escalation here, this would probably result in forbidding the use of or even destroying or incapacitating critical nodes and infrastructures required for the reception, staging, onward movement and integration of allied forces. Combining cyberattacks with targeted operations, cutting or threatening lines of communication, whether at sea or on the ground, forces would most probably occupy key terrain and close the so-called Suwalki Gap (the 65-km land corridor sandwiched between Kaliningrad and Belarus and the only land route connecting Poland to the Baltic countries) (see Veebel & Sliwa, this issue; Clark et al. 2016: 12). Eventually, all these activities would be supported and enabled by a massive cyber and (dis)information campaign targeting the public opinion in the alliance countries and trying to undermine their governments' resolution and commitment. 8

NATO and A2/AD: Understanding the Problem
Certainly, the deployment of Russian A2/AD capabilities in Syria electrified NATO member states back in 2015, as it turned out to be a real testing ground for the latest Russian arsenal (Barrie & Gethin 2018). The then SACEUR warned that NATO had to take a step back and 'take a look at our capability in a military sense to address an A2/AD challenge […]. This is about investment. This is about training' (Freedberg 2015b: para. 9). Since then the problem has been on the minds of NATO decision-makers, though they have not reached a consensus on what to prioritize. Because A2/AD crosses the span of a solely military response, overturning this challenge is complex and cannot be simply resolved. Of course, the first (and easy) solution could be to accept Admiral John Richardson's arguments, which called for a ban on using the term A2/AD. Refuting the idea of a ' one-size fits all concept', he argued that A2/AD was not generic and depended on specific adversaries within the specific context of geography, concepts and technologies. He also underlined that the concept of ' denial' was more an aspiration than an effective reality (Richardson 2016). By doing so, he emphasized that A2/AD was effectively creating more turbulent and contested areas, but he denied the very existence of true 'no-go zones' (Biddle & Oelrich 2016). His comments only underlined that A2/AD can also be seen as a true ' clash of wills', where credibility is at stake. In other words, it is about being serious and being ready to take risks -and having the political stomach to do so. Henceforth, in the case of a total war, the presence of A2/AD bubbles may not be that critical, in the sense that such bubbles would conceivably be punctured by allied air power (Majumdar 2016).
For NATO, the challenge is triple. The first obstacle is political and assumes that the alliance will always be committed to the defense of its members and therefore be able to protect them. It even goes beyond the collective defense principle or commitment to Article 5 of the Washington Treaty: It is about the core business of NATO. In the Baltic countries, NATO's role has essentially been built upon three complementing policy pillars: avoiding (unconstructive) escalation with Russia, securing the Baltic countries by taking over some of their military shortcomings (through the Air Policing mission) and guaranteeing allied access to the region. This firm political commitment has already been taken into account politically at both the Wales and Warsaw Summits through a series of decisions and pledges. For instance, in this light, the Defence Investment Pledge -a commitment to spend 2% of the national GDP on defense -can be seen as one incentive to think ahead in terms of capabilities.
The second obstacle tackles the sheer ability of NATO to refocus on deterrence and defense. Since 2014, NATO has shifted from ' assurance' to ' deterrence' through the Readiness Action Plan (RAP) adopted in Wales. Centered on the much vaunted Very High Readiness Joint Task Force (VJTF), the idea is to set what Zapfe and Haas describe as a 'mobile tripwire' that could defuse a potential crisis -not just in the Baltic countries, but potentially everywhere. The authors have a strong argument here: Beyond the narrative of ' alliance solidarity' that would make an attack on the VJTF an attack on all the major allies, they underline that the VJTF needs assured access in order to play that game (Zapfe & Haas 2016: 37). At the same time, the VJTF is small and only meant to serve as the spearhead of follow-on forces taken out of the NATO Response Force pool, which has been crippled by problems since its inception (see Lasconjarias 2013). Therefore, there is a gap -or a lack of coherence -between the major announcements (doubling the size of the NRF in a new ' enhanced NRF') and the reality -not even mentioning the loss of capabilities that have been either eroded or lost entirely. 9 This literally creates an incapacitating combination of scarcity of forces (both equipment and deployable personnel) and scarcity of enablers, as some of the identified shortfalls made at the time of the Kosovo or Libya operations still hold true (Lasconjarias & Marrone 2016).
The last obstacle is about the virtue of ensuring access by having a forward presence, at the risk of antagonizing Russia. Such decision entails a political dimension, as NATO does not want to break the 1997 Russia-NATO Founding Act by having a continuous presence in the Baltic countries. In a kind of artificial trade-off, the allies have decided to deploy rotational troops rather than establish a permanent prepositioning of forces. Since January 2017, four multinational battalions have been deployed in the Baltic countries and Poland with approximatively 4,700 soldiers from 16 nations. Called ' enhanced forward presence' (EFP), the idea is to have a permanent tripwire effect, making any territorial seizure a case of potential escalation -even if the size, volume and posture of the EFP cannot represent a sufficient military force to oppose Russian armed forces in a lasting and escalating conflict (NATO 2018). Moreover, the EFP relies on reinforcements and a logistics flow that would be at risk if Russia decided to impose an A2/AD bubble.
All in all, NATO's problem traces back to three simple challenges: At the tactical and operational level, it questions the ability of the allies to deal again with an 'un-permissive environment' -something that NATO has never really confronted. Strategically, it highlights the current lack -or insufficiency -of capabilities that would have to be opposed to an A2/AD strategy. Politically, not all NATO allies would receive enough public support in the case of a risky and likely escalation scenario: The risk of a breach in cohesion and consensus amidst the allies would result in the alliance being unable to act at all. 10

Towards a NATO Strategy to Counter A2/AD?
A counter-A2/AD strategy cannot be separated from larger reflections on improving deterrence. In addition, as NATO insists on being a defensive alliance, it has to adapt to a complex situation without escalation. However, and for the sake of the exercise, an A2/AD strategy could possibly follow two complementary paths: The first path would be a pure military and technological adaptation to the new threat, shifting for good from a capability-focused approach to a threat-focused one. The second step would be more political with decisions that would immediately respond to any Russian intrusion on NATO's territory, which would be preceded or followed by the set-up of an A2/AD bubble.
From a military viewpoint, Russian A2/AD is a concrete threat because Moscow's integrated air defense system and short-range land attack missiles already cover the Baltic countries in their entirety as well as large swathes of Polish territory. Some interactive maps insist on showing that if medium-range missiles are included in the A2/AD package, then most European capitals are at risk, a problem further complicated by 9 See e.g. a statement for the land forces in Lasconjarias (2015). Most of the conclusions made by Christian Mölling (2011)  the deployment of mobile A2/AD systems along Europe's eastern and southern flanks (Simón 2017: 129 and the interactive CSIS Missile Threat map). Four domains should therefore be prioritized in order to cope with the A2/AD bubble: -Revisit NATO air presence in the Baltic countries and allied air doctrine. As of today, NATO's air presence in the Baltic countries is a peacetime mission that has to be reinforced. It is true that since 2014 the number of fighter jets assigned to the mission has increased, but the nature of the mission itself has not changed fundamentally. Some recommend transitioning the air policing to an air defense mission with additional efforts in training and exercises (Clark et al. 2016: 22). Moreover, only a few nations possess the knowledge and the means to perform effective Suppression of Enemy Air Defenses (SEAD) and Airborne Electronic Attacks (AEA) -all the missions that would have to be performed to penetrate the A2/AD bubble. Past campaigns such as operation Unified Protector have proved how critical these means are and how even more vital they will be in the near future. -Reconsider NATO's maritime strategy. In order not to turn the Baltic Sea into a Mare Russam, NATO has beefed up its maritime dimension through the missions assigned to the two Standing Naval Groups (one for the north and one for the south), alongside the two Standing NATO Mine Countermeasures Groups. MARCOM (Northwood, UK) has done a lot of work in rethinking the basics of anti-submarine and anti-surface warfare, but NATO's maritime doctrine at large should be revised. -Improve our communications, radar and electronic attack systems. In the past two decades, NATO has reached an unprecedented level of connectivity, if the operations in Afghanistan and Iraq serve as a model. If NATO found itself facing an adversary like Russia, the level of our dependency would be very striking -as some lessons learned during combat in Ukraine prove (Eckel 2018). Because Russian electronic warfare capabilities are active in the air, on the sea, on the ground and in cyberspace, NATO must not simply share knowledge and expertise, but also identify gaps and find remedies to fight in a communication-degraded environment. -Learn to fight big again. NATO's rotational presence and its reinforcements do not exceed the size of battalions. The VJTF itself is a brigade-size, multinational unit that would be no match to its Russian equivalent, if one takes into consideration that Russia has been increasing significantly through snapshot exercises the possibility of training up to hundreds of thousands of troops. Due to the past 14 years in Afghanistan, where NATO focused on battlegroups, it must now train again at the brigade division level, with classic rehearsals of defense/delay/attack operations. Surely, NATO has improved its exercise program and recognized the need to multiply the number and size of exercises. Since 2014, NATO and allies have performed hundreds of exercises, a peak being reached with the latest Trident Juncture 2018, the largest since the end of the Cold War. 11 Of course, in order to make this new posture more robust, NATO allies should also think about capability development (see Lasconjarias & Marrone 2016). The NATO Defence Planning Process (NDPP) brings cohesion across the various strands of work, but could perhaps be more focused and reflect changing concerns and priorities. For the past two decades, NATO capabilities have mainly been orientated toward crisis management and expeditionary warfare. Today, the changing and hardening environment pushes for heavier equipment and keeping the assets and means that would guarantee access to operational theaters. This means that a new balance must be established between the two core tasks of collective defense and crisis management, also bearing in mind that several capabilities serve both purposes. Politically, NATO could chart another course in going after more coercive measures against Russia -which nobody foresees or would dare to suggest (Lasconjarias & Marrone 2016). If Russia should continue its destabilization policy at its borders and beyond (in Ukraine and around the Black Sea), NATO could decide to go for a 'horizontal escalation' in temporarily blockading the Baltic Sea -even if this would most certainly be considered an act of war. Some former NATO officials thought this would complicate Russia's calculus and might lead to a downward spiral which would leave little room for dialogue and progress toward a political settlement. Another option would follow an intrusion by Russian forces on NATO territory -such as the grasp of one of the Baltic countries' territory. As Stephan Frühling and I have argued in a recent article, Kaliningrad could be a perfect trade-off, as the exclave is both a threat and a hostage to NATO (Frühling & Lasconjarias 2016; see also Sukhnakin, this issue). The geographic isolation of Kaliningrad creates a strategic dilemma for Russia: Kaliningrad threatens to isolate the Baltic countries at the beginning of a conflict, but that threat has to remain latent until Russia actually attacks NATO's air, naval or land forces from the enclave. To do so, however, would mean tearing up any tacit agreement with NATO on limiting the geographic scope of a conflict and risking the loss of the Kaliningrad enclave once NATO mobilizes sufficient forces in the area. Conversely, for NATO, this means that the best way of dealing with the Russian A2/AD threat in the Baltic would be to isolate Kaliningrad as soon as possible in wartime and to threaten the invasion of the territory in order to deter Russia from conducting military operations from the enclave in the first place. And the reaction of Russia to such a NATO strategy could immediately get out of hand, with rapid and perhaps uncontrolled escalation, even threatening to use tactical nuclear weapons -something Russia has never excluded. Again, as Zapfe and Haas put it, Any semi-public war planning that focuses on threatening Kaliningrad as the basis for deterring Russia would grievously dilute the defensive purpose of NATO strategy -as distinct from the means of its execution, which will have to be partly offensive -and presumes the will to escalate massively at the very outset of a conflict, with few other options left in hand (Zapfe & Haas 2016: 39).

Conclusion
A2/AD is not a new concept, but it has reached a new stage with Russia's aggressive stance and could represent a strategic issue for Euro-Atlantic security, as it can be identified as one of many ways to challenge the West (and the US) at every level, from the tactical to the strategic, on NATO's doorstep. Even if denying someone freedom of movement has always been part of the history of warfare, A2/AD changes the scale, lethality and scope of the threat, with some risk of uncontrolled escalation.
From a NATO perspective, A2/AD is both a challenge and a threat. It is a challenge because we continue to debate whether it constitutes a military or also a political issue, which does not ease the nature of possible responses. As Russia seems to play both hybrid tactics that are below the threshold of NATO's response and the A2/AD card that could be considered as overt conventional means, NATO's response has to be comprehensive at the political, strategic, conventional and nuclear levels. Every gap would be seen as a wedge that Moscow could leverage. It is not just about NATO's freedom of action being hampered; it is about the possibility to reinforce allies when they are under threat. If NATO cannot fulfill this, it will undermine its credibility and its raison d'être.
What is certain is that NATO cannot choose to do nothing. Doing nothing would weaken alliance resolve, have consequences for how the alliance reassures its members and create a divided NATO between the countries that are willing to adopt a firmer stance vis-à-vis Russia and those that are more adamant to negotiate due to common issues. Politically speaking, countering A2/AD means raising the costs of any potential military action from Moscow against a NATO member and have the narrative and information campaign to spin it off. Militarily speaking, A2/AD is a unique chance to assess the allies' vulnerabilities and how they can overcome any shortfalls. A2/AD stresses the need for NATO nations to acknowledge that the alliance's superiority in a number of domains is going to be challenged -the question is not 'if', but 'when'.
The real issue concerning A2/AD is that the concept is based on a sequence of events which ends with the establishing of a bubble. From a NATO perspective, there are three possible options. First, and because of the profoundly defensive nature of the alliance plus the rather cumbersome decision-making process, crisis would occur when the bubble illuminates. Yet, other allies would probably already have moved in, allowing the rest of the nations to join afterwards. As in the case of Crimea, the US would send their European-based fire brigade (the 173 rd Airborne) alongside some vessels plus the high alert for jetfighters. The UK and perhaps France would join sooner rather than later in a fashion that resembles what happened in Libya in 2011. On the other hand, if none of the above-mentioned react, it would have deep repercussions in the alliance, leading to its dismissal. Second, if caught by surprise and unable to respond in a proper way, NATO forces would be forced to either surrender, flee or suffer defeat; the game should avoid direct confrontation and a slow built-up of forces to retake by force the lost states. Not only would that take months, but the Russian doctrine to escalate to de-escalate would probably include a nuclear dimension which might result in cold feet allies. In this case, horizontal escalation would be useful, either by playing quid pro quo, by threatening Russian forces in Transnistria, in the Caucasus by helping Georgia, up to directly intervening in Ukraine (Pothier 2017). Rather than focusing on capabilities, both military and diplomatic pressure would make the cost less than acceptable to Russia. Last, A2/AD can only be seen as a deterrent if the NATO allies, taken as a whole and individually, are ready to drop every red line they establish -and Syria remains a painful memory. In other words, A2/AD is a litmus test that aims at making NATO (over)react. On the contrary, if the allies have the guts to go ' all in', A2/AD will neither be decisive nor essential. Again, learning from history and doing our homework should help prevent any risk of miscalculation.