The West, Russia and European security: Still the long peace?

Against the background of increased tensions between the West and Russia, this article assesses the prospects for continued peace in Europe. The end of the East-West conflict upended the Cold War rules of the game in Europe’s east, creating an enduring source of conflict. Balanced against this, however, are a range of factors which act as powerful bulwarks against war: a European balance of power best characterised as modified bipolarity, the continued pacifying effect of nuclear weapons, energy interdependence between Russia and Europe, the deterrent effect of the likely consequences of any extended conventional war, and the continuing impact of the post-1945 satellite reconnaissance revolution. Post-Cold War Western and Russian crisis behaviour also suggests important elements of restraint and mutual communication. Despite the downturn in Russo-Western relations, one can be cautiously optimistic that the long peace in Europe will continue.


Introduction
The downturn in relations between the West and Russia in recent years, which some describe as a new Cold War (Legvold, 2016), has led to renewed concern about the possibility of major war in Europe. Since the conflict over Ukraine in 2014, most of the institutional ties between the West and Russia that were put in place in the 1990s and 2000s have been frozen or abandoned, the United States and the European Union (EU) have imposed financial and other sanctions on Russia, and North Atlantic Treaty Organization (NATO) and Russia have intensified military deployments and planning for a possible war with one another. Russian and Western military activities have resulted in a significant increase in close military encounters in the air and at sea, which analysts fear could trigger an unintended conflict (Frear et al., 2014;Raynova and Kulesa, 2018). Some observers have warned of scenarios involving war between Russia and NATO which could escalate to the use of nuclear weapons (British Broadcasting Corporation, 2016;Shirreff, 2016).
Drawing on the growing literature on the conditions of peace between states, as well as Gaddis' Cold War long peace thesis (Gaddis, 1986(Gaddis, , 1991, this article assesses the prospects for war and peace between Russia and the West in Europe in the 2020s and beyond. The first section of the article reviews the literature on the sources of peace between states, identifying those factors most relevant to contemporary Western-Russian relations in Europe. The next section shows how the contested nature of Europe's post-Cold War order has created an enduring source of tensions and potential conflict between the West and Russia. The following sections examine three factors that I argue make war between the West and Russia in Europe unlikely: the contemporary European balance of power, which is best characterised as modified bipolarity and has important stabilising consequences; the continuing pacifying impact of nuclear weapons; and the energy relationship between Russia and the West, which is best understood as one of interdependence (rather than simple Western dependence on Russia). Combined with two things that have not changed -the deterrent impact of the likely consequences of any extended conventional war and the reduced risk of surprise or pre-emptive attack arising from the development of reconnaissance satellites -these factors are significant forces likely to impose caution on Russian and Western leaders and thus act as important bulwarks against the risk of war between Russia and the West.
This article also examines Western and Russian behaviour in crises involving the use of force since the end of the Cold War, showing that, despite divergent positions and resulting tensions, there have also been important elements of restraint and mutual communication by both the West and Russia in such crises -suggesting that both sides are aware of the risks of escalation and have taken steps to avoid war. The possibility of war between Russia and the West in Europe should not be entirely discounted and governments should work to maintain channels of communication and establish confidencebuilding measures (European Leadership Network, 2020). Nonetheless, despite the serious downturn in Russo-Western relations in recent years, one can be cautiously optimistic that the long peace between Russia and the West in Europe will continue.

The conditions of peace: The Cold War and beyond
Recent decades have produced a large body of literature on the conditions of peace between states. Steven Pinker's book The Better Angels of Our Nature: Why Violence Has Declined, in particular, gave new prominence to the argument that war was declining as a phenomenon in world politics (Pinker, 2011). Other authors have advanced broadly similar arguments, in particular that inter-state war is declining and especially that great power war has become increasingly unlikely (Goldstein, 2011;Jervis, 2001;Mandelbaum, 2019;Mousseau, 2019;Mueller, 1990). The range of factors viewed as causes of peace include the balance of power, nuclear weapons, the increasing destructiveness of conventional warfare among industrialised states, democracy, international institutions, and economic interdependence. This section reviews this literature (as well as Gaddis' long peace argument), highlighting those factors most relevant to Europe during the Cold War and to the post-Cold War relationship between the West and Russia.
The Cold War was distinguished from previous periods by bipolarity and nuclear weapons and these factors became a particular focus of explanations for the US-Soviet long peace. The emergence of the United States and the Soviet Union as the world's two superpowers after 1945 and the division of much of the world into East and West prompted debate on whether bipolarity -as opposed to the historically more common pattern of great power multipolarity -was a cause of peace. Neo-realist theorists, in particular Kenneth Waltz, argued that bipolar systems are characterised by the preponderant power of the two dominant powers, an absence of peripheries, the extended range and intensity of competition between the two powers, and persistent pressure and crises, which together produce a system in which the likelihood of direct war between the two dominant powers is low (Waltz, 1964(Waltz, , 1979. Gaddis concurred, arguing that '(T)he great multipolar systems of the 19 th century collapsed in large part because of their intricacy', whereas '(T)he post-1945 bipolar structure was a simple one that did not require sophisticated leadership to maintain it'; that the simplicity of the bipolar structure resulted in more stable alliances; and that the predominance of the two superpowers and the overall stability of the alliance system meant that the United States and the Soviet Union could tolerate defection by individual powers from their respective alliance systems (Gaddis, 1986: 108-110). Critics, however, argue that the logic underpinning the argument that bipolar systems are inherently less war-prone than multipolar ones is not persuasive and that historical evidence does not support this proposition (Kegley and Raymond, 1992). An additional balance of power related factor was US hegemony: the predominant power of the United States, it is argued, enabled it to act both as a stabilising power within the West (in particular, through NATO in the European context) and to deter the Soviet Union (Jervis, 2001;Mandelbaum, 2019).
Prominent international relations scholars argue that nuclear weapons, the second factor distinguishing the Cold War from earlier great power relationships, have had a revolutionary impact on international politics among nuclear armed states. The unprecedented destructive potential of nuclear weapons and the risk that any conflict among nuclear armed states may escalate to nuclear war, it is argued, imposes extreme caution on political leaders, effectively ruling out war as an option between such states (Jervis, 1989;Mandelbaum, 1982;Waltz, 1990). Likewise, Gaddis argued that the nuclear age reduced 'the willingness to risk war that has existed at other times in the past' and imposed 'unaccustomed caution' on the United States and Soviet leaders (Gaddis, 1986: 120-121). Some argue that other factors explain the Cold War long peace and that nuclear weapons consequently had a marginal role if at all (Mueller, 1988), but this is a minority view.
Even putting aside nuclear weapons, there is an argument that the likely consequences of a major conventional war are also a significant force for peace. The increasing destructiveness of large-scale conventional war among advanced industrialised states and the scale of destruction in the Second World War have made publics and political leaders deeply wary of such warfare and thus make decision-makers very cautious in situations which might escalate to such a conflict (Mueller, 1990).
An additional factor is what Gaddis termed the 'reconnaissance revolution'. The post-1945 development of reconnaissance satellites provided the superpowers with an unprecedented degree of information about each other's militaries, arguably significantly reducing the likelihood of a successful surprise attack or of war arising because of misperception of the other side's military plans or activities. Despite the relative lack attention paid to the 'reconnaissance revolution' as a cause of great power peace, Gaddis (1986: 123) argued that it 'may well rival in importance the "nuclear revolution"'.
Three other factors which are widely viewed as producing peace between states are the liberal triad of democracy, international institutions, and economic interdependence (Russett and Oneal, 2001). Of these three factors, there is particularly strong evidence to support the democratic peace hypothesis that democracies do not go to war with one another (Hegre, 2014), but also evidence to support the arguments that international institutions and economic interdependence reduce the likelihood of war between states (Gartzke, 2007;Mousseau, 2019) -although all three propositions remain, to some extent, contested. The liberal triad of democracy, international institutions, and economic interdependence, plus the hegemonic role of the United States, has also resulted in the emergence of a security community -a group of countries between whom war has effectively moved off the map of political possibilities -in the West (defined as North American, Western (and now also Central) Europe, Japan, and the United States' Asian allies) (Deutsch, 1957;Jervis, 2001).
The relevance of the liberal triad of democracy, international institutions, and economic interdependence to the Western-Russian relationship, however, is limited. During the Cold War, none of these factors could be said to be present between East and West. In the 1990s, Russia began to democratise, but the consolidation of an authoritarian regime under the leadership of President Vladimir Putin precludes (at least for now) a democratic peace between Russia and the West. Although NATO and the EU established institutionalised ties with Russia in the 1990s to 2000s and Russia and Western states are members of the United Nations (particularly the United States, France, and the United Kingdom alongside Russia as permanent members of the UN Security Council), these ties lack the deep institutional density that exists within the West and have largely been suspended since the start of the Ukraine conflict in 2014. Economic relations also lack the type of deep economic interdependence that exists within the EU and between Europe and the United States. In the area of Russian energy exports to Europe, however, a form of economic interdependence does exist and, as discussed in more detail later, may have a pacifying impact on Western-Russian relations.
In the specific context of the Cold War, analysts have advanced a number of additional arguments as to why that conflict did not escalate to war, in particular, that both superpowers moderated their policies in favour of peaceful coexistence (to use Soviet leader Nikita Khrushchev's term; Gaddis, 1986: 125-132;Leffler, 1992;Mastny, 1998). Gaddis (1986: 132-139) argues that informal 'rules' of the 'game' emerged over time, including respecting the other side's sphere of influence, avoiding direct military confrontation, using nuclear weapons only as a last resort, accepting anomalous situations in the interests of avoiding conflict, and refraining from undermining the other side's leadership. Other analysts have also argued that the US-Soviet Cold War relationship involved significant elements of informal cooperation and the development of East-West security regimes (in particular, arms control agreements) (Kanet and Kolodziej, 1991).
In summary, a wide variety of factors are viewed as causes of peace between states, but the persuasiveness of various theories and the relative importance of different factors remain contested. There is a degree of consensus that war is unlikely within the Western security community, but whether that applies to the West's relationship with Russia and China is less certain (Jervis, 2001;Mandelbaum, 2019).

The post-Cold War European order: Contested rules
The central factor which has made conflict between the West and Russia likely once again has been the contested nature of the post-Cold War European order. During the Cold War, one of the central rules of the game was de facto acceptance of the other side's sphere of influence, with both the Soviet Union and the West at least partly refraining from challenging the other's sphere (Gaddis, 1986: 133-134). With the end of the Cold War, the previous game and its associated rules collapsed. From the Western perspective, the post-Cold War European order was (or ought to be) based on democracy and human rights, voluntary cooperation and integration among states, and the right of states to choose their domestic political systems and foreign policy orientations. In contrast, Russia's approach has been based on a more classical sphere of influence perspective. Although the Soviet leadership acquiesced in the fall of the Central and Eastern European communist regimes and the re-unification of Germany in 1989-1990, Russia never fully accepted the loss of its sphere of influence, in particular in the former Soviet space. Russia thus opposed NATO (and to some extent also EU) enlargement into Central and Eastern Europe, NATO's intervention in former Yugoslavia and Western democracy promotion efforts in the former Soviet Union. This provided the context for subsequent Russo-Western tensions over the former Soviet region and especially the Ukraine conflict in 2014 (D'Anieri, 2019). These geo-strategic differences between the West and Russia are now deeply embedded (Sakwa, 2017).
Given that Western governments would now find it difficult to accept the former Soviet space as a Russian sphere of influence and Russia is unlikely to accept Western 'interference' in the region, the re-establishment of the old rules of the game seems unlikely. Some Western analysts, however, argue that NATO should foreswear further eastward enlargement as part of a new grand bargain with Russia (O'Hanlon, 2017). Such an approach would follow the logic of re-establishing (new) geo-political rules of the game with Russia. Even if Western governments may be reluctant to foreswear further NATO enlargement, they have, in practice, been cautious about advancing possible Ukrainian and Georgian membership of NATO. Furthermore, as is discussed below, in the 2008 Georgia war and the Ukraine conflict since 2014, Western governments have refrained from military intervention and been cautious in providing military assistance to Ukraine and Georgia -suggesting that some of the old rules of the game (in particular, caution about the use of force) remain at least partly intact. Nonetheless, the contested nature of the contemporary European order is likely to remain an on-going source of tension between Russia and the West.
A second Cold War rule of the game was refraining from efforts to undermine the other side's leadership or, more broadly, from interfering in the other side's domestic politics (Gaddis, 1986: 138-139). With the end of the Cold War, the West viewed itself as freed from this rule and explicitly supported democratisation in Russia, including by backing Boris Yeltsin in the 1996 Russian presidential election (Beinart, 2018), providing assistance to civil society groups and other independent institutions under President Vladimir Putin (Nichol, 2006), and supporting democratic 'colour revolutions' elsewhere in the region (Stewart, 2009). The Russian leadership has strongly opposed Western democracy promotion in Russia and the other former Soviet states. The Western breaking of the previous rules of the game was presumably also a factor behind more recent Russian efforts to influence elections in the West, in particular, the 2016 US presidential election, but also a number of European elections (Lamond and Dessel, 2019;Mueller, 2019). Whether the breakdown of the informal rule against interference in domestic politics necessarily makes war more likely can be debated, but at minimum it is now an important element of mistrust between the West and Russia, with both sides believing that the other seeks to undermine their political system.

The new European balance of power
How did the end of the Cold War alter the European balance of power and how has the European balance of power evolved in the three decades since then? As discussed earlier, various analysts viewed bipolarity as a force for stability during the Cold War. Neorealists, most prominently John Mearsheimer, argued that with the end of the Cold War Europe would return to multipolarity, making great power war more likely (Mearsheimer, 1990(Mearsheimer, : 7, 13-18, 51-52, 2001. The neo-realist argument that the end of the Cold War has resulted in the re-emergence of a multipolar Europe, however, reflects a crude understanding of the balance of power and is not convincing. If one considers the balance of power solely in terms of the relative distribution of power, it is clear that the power of post-Soviet Russia declined dramatically, the power of the re-united Germany increased (very significantly relative to Russia, in a more limited way relative to the United States, the United Kingdom, and France) and the relative power of the United States, the United Kingdom, and France increased significantly relative to that of Russia and declined somewhat relative to that of Germany.
To equate these relative shifts with a return to multipolarity, however, is simplistic. Polarity needs to be understood not simply in terms of the relative distribution of power, but also in terms of the number of autonomous decision centres (Brecher et al., 1990). From this perspective, the shift in the material balance of power with the end of the Cold War did not increase the number of independent decision centres in Europe. This can be seen in a number of developments, all of which run contra to the neorealist logic of a return to multipolarity. First, NATO has survived and continues to play a central role in European security (Thies, 2009). Second, the European Union has not only survived, but has also deepened cooperation, including in the field of foreign, security, and defence policy (Keukeleire and Delreux, 2014). Third, despite periodic crises within the West (e.g. over the Yugoslav conflict, the Iraq war, and the euro), such crises have not triggered a wider break-up of NATO, the EU, or the West (Davis Cross, 2017;Thies, 2009). Fourth, the more powerful re-united Germany was the prime candidate to become an independent decision centre. Yet, if one examines German foreign and security policy since the end of the Cold War, the defining feature has been Germany's continued commitment to and integration in NATO and the EU and the wariness of Germany's leaders of pursuing policies independent of its Western partners (Crawford, 2007).
The same point is illustrated if one considers alignment options and alliance patterns. In significant part, what defined bipolarity in Cold War Europe was that there were only two alignment options -the US-led West and the Soviet Union. The majority of countries were members of NATO and the Warsaw Pact, there was no third alignment option and a small number of countries chose to remain neutral or had neutrality imposed upon them. If post-Cold War Europe had returned to multipolarity, one might have expected the alliance options open to states to increase and changes in alignment to occur more frequently: Russia, France, and Britain might have aligned against Germany (as they did in the First and Second World Wars), Germany and Russia might have aligned with one another (as they did under the 1922 Rapallo Treaty and in 1939), smaller states might have pursued a variety of alliance options, and so on. The evidence from three post-Cold War decades suggests the opposite: Germany, France, Britain, and the rest of NATO's members have remained committed to the alliance and none has pursued alternative alliance options; consequently, Russia has not had the possibility of pursuing alliance options with any of the major Western European states against others; and smaller states, therefore, have not had multiple great power alliance options open to them.
In terms of polarity, 30 years of post-Cold War experience suggests that it makes much more sense to think of the West (defined broadly, in the European context, as NATO and the EU) as a single pole, rather than Germany, France, Britain, and the United States as independent poles. In relative power terms, further, the gap between the combined power of the West (the members of NATO and the EU together) and that of Russia has been such that contemporary Europe might be viewed as unipolar, revolving around the dominant Western pole. Given Russia's large geographic size, still substantial military power (including nuclear weapons) and economic power (albeit much reduced compared to the Soviet Union), however, it still makes sense to think of Russia as a great power or pole in contemporary Europe. In this sense, contemporary Europe may best be understood in terms of modified bipolarity; the rough parity between East and West of the Cold War and the sharp division of the continent into two alliances may be gone, but in terms of poles and alliance choices, Europe is still characterised by two centres of power, the West and Russia.
If bipolarity is more stable than multipolarity, in particular because the alliance choices open to states are reduced and alliance management and crisis management are simplified, the continued bipolarity of contemporary Europe may make the Russo-Western relationship less likely to produce war than some have predicted. Furthermore, the large disparity of power between the West and Russia likely acts as a deterrent to Russia pursuing ambitions of continent-wide hegemony; whereas the Soviet Union might hypothetically have hoped to prevail in continent-wide conventional war during the Cold War, the overall balance of military and economic power between the West and Russia today is such that Russia would stand little chance of winning any continent-wide war (as is discussed further below, Russia might have hopes of prevailing in more localised wars, in particular, over the Baltic states).
Additional factors here are the emergence of a multipolar order at the global level and the rise of China. For European international politics, this involves two elements: the increasingly close relationship between Russia and China and China's growing presence in Europe (in particular, in terms of trade, investment, and infrastructure; Le Corre and Sepulchre, 2016). Nonetheless, while China is likely to be a growing factor in European international politics, this is unlikely to fundamentally alter the balance of power dynamics discussed earlier. Even if Russia and China were to conclude a formal alliance agreement, it is difficult to conceive that this would make Russia significantly less risk averse regarding the possibility of major war with the West. For other European states, China may be an economic partner, but, again, it seems unlikely that China's presence will reshape security policy choices in a way that would make major war more likely in Europe.

The continuing impact of nuclear weapons
Nuclear weapons, of course, were central to the Cold War in Europe. From the 1950s onwards, the United States and the Soviet Union not only developed large long-range strategic arsenals but also deployed large numbers of so-called tactical or theatre nuclear weapons in Europe (aircraft deployable nuclear bombs and nuclear warheads on shorter range missiles). These developments ensured that there was a significant risk that any East-West war in Europe would rapidly escalate to nuclear war. There were continual concerns about the credibility of nuclear deterrence, in particular whether the United States/NATO would risk a nuclear response to a Soviet conventional attack in Europewhich was why the United States and NATO switched from an initial nuclear strategy of massive retaliation to one of flexible response (Freedman and Michaels, 2019). As noted earlier, however, the mainstream view is that nuclear weapons were a significant factor behind the Cold War long peace in Europe and globally.
With the end of the Cold War, the United States and Russia significantly reduced their strategic nuclear arsenals and withdrew and dismantled large parts of their theatre or nuclear arsenals. Under the 1987 Inter-mediate range Nuclear Forces (INF) treaty, the United States and the Soviet Union agreed to dismantle all medium-range nuclear capable missiles, including US missiles forward-deployed in Europe and Soviet missiles deployed in Eastern Europe. Under the 1991 Presidential Nuclear Initiatives (PNIs), the United States and Soviet leaders agreed to dismantle all short-range nuclear missiles and to withdraw from deployment tactical nuclear weapons on ships and submarines. The result was a radical reduction of tactical or theatre nuclear weapons and the withdrawal of most forward-deployed nuclear weapons, leaving the United States with about 200 aircraft deployable nuclear bombs in Europe and Russia with a larger arsenal of about 1800 tactical nuclear warheads (Kristensen and Korda, 2019). The result of these developments might be viewed as reducing the likelihood that any conflict between NATO and Russia would escalate to nuclear war, but thereby making a conventional war less risky and consequently more likely in a crisis. Notwithstanding the significant post-Cold War nuclear reductions, however, the risk that any conflict between Russia and NATO would escalate to nuclear war remains and the consequences of a nuclear war are such that this risk likely continues to impose great caution on Russian and Western leaders -as various analysts have argued, nuclear deterrence is almost certainly easier to maintain than persistent concerns over its credibility might suggest (Jervis, 1985;Waltz, 1990).
In the context of the recent downturn in relations between Russia and the West, nuclear weapons have again begun to assume a more prominent place. Russia, in particular, has placed an increased emphasis on nuclear weapons in its military policy, by, for example, explicitly including first-use in its strategy, Russian leaders rhetorically referencing the use of nuclear weapons, conducting military exercises involving the simulated use of nuclear weapons and, since the late 2010s, deploying Iskander nuclear capable missiles in Kaliningrad (with the capacity to target NATO capitals such as Warsaw, Berlin, and Copenhagen). From the early 2010s, the United States and its NATO allies argued that Russia was violating the INF treaty by developing missiles prohibited by the treaty, leading to the United States withdrawal from the treaty in 2019 and its effective collapse. In the West, these developments have generated concerns that Russia may be increasingly willing to engage in limited first use of nuclear weapons to settle a conventional war on its terms, based on the assumption that NATO will not retaliate because of the risk of wider nuclear escalation. Informed Western observers, however, suggest such concerns over Russian willingness to use nuclear weapons are exaggerated: (T)here is no gimmicky 'escalate to win' strategy . . . (T)he Russian military has a visibly different comfort level with nuclear weapons than does the United States . . . but it does not write off nuclear escalation in recklessly optimistic terms, incognizant of the associated risks. (Kofman and Fink, 2020) A number of other developments have generated concern about a new era involving increased risks of nuclear war (Zala, 2019). These include the United States/NATO deployment of ballistic missile defences, the development of hypersonic and long-range precision strike weapons, the possible deployment of nuclear capable cruise missiles (following the collapse of the INF Treaty), anti-satellite weapons, the incorporation of artificial intelligence (AI) into nuclear command and control systems, and cyber warfare. These developments may increase the risk of escalation to nuclear war in a crisis and point to the need for new arms control measures to address these issues. Nonetheless, on balance, there remains a strong case that nuclear weapons continue to have a powerful pacifying effect on the relationship between Russia and NATO.

Economic and energy interdependence
As discussed earlier, there is a significant evidence to support the hypothesis that economic interdependence between states produces peace, although the argument remains contested. During the Cold War, economic ties between the Soviet Union and the West were very limited. Trade between Russia and the EU (as well as non-EU NATO members such as Norway, Turkey, and the United Kingdom (which officially left the EU on 31 January 2020)), however, has grown quite significantly since the end of the Cold War. Russia is the EU's fifth largest trade partner and the EU is Russia's largest trade partner (European Commission, 2020;Forsberg and Haukkala, 2016). Whether the scale and nature of economic ties between Europe and Russia is such that it has the peace producing impact said to arise from economic interdependence can be debated. The EU's trade with Russia is significantly less in scale than its trade with the United States or China (about one fifth of the amount in each case). The EU's trade with Russia is also much less broadly based and diversified than that with the United States and China, with energy (gas and oil) constituting by far the largest part of Russian exports to the EU. European-Russia economic ties therefore perhaps do not involve the truly wide ranging economic interdependence (and associated societal ties and interests) which may produce peace. It should be noted that while the EU imposed targeted financial sanctions on Russia in response to Russia's 2014 intervention in Ukraine, these did not include wider economic sanctions and have not radically disrupted EU-Russia trade (European Commission, 2020).
The European-Russian energy relationship dates from the late-Cold War period. In the 1980s, despite US opposition, Western European states helped establish a major trans-Siberian pipeline to supply gas from Russia (Gustafson, 2020;Högselius, 2013). Central and Eastern European states also continue to depend on gas supplies from Russia through pipelines built during the communist era. Consequently, EU member states import approximately 40% of their gas from Russia, with Central and Eastern European states importing most of their gas from Russia, Germany about 50% and other Western European states lower percentages (Eurostat, 2020). Russian-European energy interdependence has been further increased by the construction of the Nord Stream gas pipeline from Russia to Germany under the Baltic Sea, which became operational in 2011-2012, with a parallel Nord Stream 2 gas pipeline under construction, which may become operational in the early 2020s. In addition, Russian energy companies, in particular Gazprom, have invested significantly in European energy infrastructure and production.
In Europe and the United States, these developments have resulted in growing concern about European dependence on Russian gas and the political leverage this arguably gives Russia (Baran, 2007). The relationship, however, is better understood as one of mutual dependence or interdependence (Casier, 2011): gas and oil exports are a core element of Russia's economy and a key source of revenue for the Russian state; any sustained suspension of gas supplies to Europe (whether through a Russian attempt to exercise political leverage over Europe or in the event of war between Russia and the West) would have a very significant negative impact on the Russian economy. The potential economic impact of the disruption of energy ties is likely to be a significant restraining factor in any situation where armed conflict is likely between Russia and NATO. As Michael Sulick (2016) puts it, 'Russia is just as dependent on Europe's energy market as Europe is on Russian energy supplies . . . (G)iven this interdependence, Russian sabers will surely continue to rattle against NATO, but steel won't strike steel'. Since the 2010s, European countries and the EU have sought to reduce dependence on Russian gas and the Nordstream 2 pipeline has faced strong opposition from the United States and some European countries. Nevertheless, European-Russian energy interdependence is likely to remain a reality for some time (Gustafson, 2020).

Crisis behaviour: Mutual restraint
Another way of assessing the risk of war between the West and Russia is to examine the two sides' behaviour in crises since the Cold War where one or other has used force and escalation to conflict between them might have occurred. The main crises in this category are those in Bosnia-Hercegovina in 1994-1995, Kosovo in 1999, Georgia in 2008, Ukraine since 2014, and Syria since 2015 In all these crises, both the major Western powers and Russia have behaved with restraint and to varying degrees taken concrete steps to avoid escalation to direct conflict with one another. In Bosnia-Hercegovina in 1994-1995, NATO used airstrikes to halt Bosnian Serb attacks and coerce a peace settlement and then deployed a nearly 60,000-strong force to enforce the peace settlement. Russia opposed NATO's airstrikes and was more generally wary of NATO's encroachment into the Balkans, but refrained from taking any direct action to undermine or interfere with NATO's air operations (Bowker, 1998). Despite their differences over Bosnia-Hercegovina, the West sought, at least partly, to include Russia in decision-making. The mandate for the NATO peacekeeping force was agreed with Russia in the United Nations Security Council, Russia was included in the international Peace Implementation Council (PIC) overseeing the peace settlement and Russia contributed troops to the NATO peacekeeping force from 1995 to 2003 (Cross, 2002).
In Kosovo, in 1999, a similar pattern played out. Again, NATO used airstrikes to halt Serbian attacks and coerce a peace settlement and then deployed a 55,000-strong force to enforce the peace settlement. Russia opposed NATO's airstrikes in Kosovo even more strongly than it had opposed those in Bosnia-Hercegovina, but again refrained from taking any direct action to undermine or interfere with NATO's air operations. At the height of the conflict in May to June 1999, when it was unclear how the war might end, Russian diplomacy played an important role in persuading Serbian leader Slobodan Milosevic to accept a peace agreement, including the deployment of a NATO peacekeeping force (Norris, 2005). In early June, as the war ended, the so-called 'race for Pristina' incident occurred: without agreement or consultation with NATO, Russia re-deployed 250 troops and armoured vehicles from its forces in Bosnia-Hercegovina to take control of Pristina airport; NATO troops surrounded the Russian forces; NATO's Supreme Allied Commander Europe US General Wesley Clark ordered the use of force to take control of the airport; the NATO commander on the ground UK General Mike Jackson refused, apparently telling Clark 'I'm not going to start the Third World War for you'. The Russian forces, however, were surrounded and unable to re-supply themselves with water or food and thus within a few days agreed to hand Pristina airport over to NATO control (British Broadcasting Corporation, 2000). Modalities were subsequently agreed for Russian participation in the NATO force in Kosovo and Russian forces served there until 2003 (Cross, 2002). Although the Kosovo war illustrates elements of restraint by both Russia and NATO and General Jackson's comments about a possible 'Third World War' are arguably hyperbole (since Russia's credible options for retaliation appear to have been limited), the 'race for Pristina' incident might potentially have played out differently, resulting in a firefight between NATO and Russian forces and possibly further escalation -highlighting that a peaceful outcome of such situations should not be viewed as predetermined.
The 2008 Georgia war indicated a new Russian willingness to use military force in the former Soviet region, but again both Russia and Western states showed restraint and were able to establish elements of cooperation (Asmus, 2010;Cornell and Starr, 2009). Although Russia invaded Abkhazia and South Ossetia (the Russians argued that their action was a humanitarian intervention to protect the populations of Abkhazia and South Ossetia) and subsequently recognised the two entities as independent states, it refrained from the potential maximalist objective of driving on for the Georgian capital Tbilisiensuring that the war lasted only 5 days. Senior US officials considered military action, in particular, bombing the Roki Tunnel (the key route through which Russian forces were able to travel) or other 'surgical strikes', but quickly ruled these out given the risks of direct armed conflict with Russia (Asmus, 2010: 177-179 and 186-191;Smith, 2010). European states and the United States also sought to work with Russia in concluding a cease-fire agreement with Georgia, with French President Nicolas Sarkozy (representing the EU, as France at that point held the 6-monthly rotating EU Presidency) playing a leading role (Asmus, 2010: 189-214). In addition, from October 2008, an EU monitoring mission (EUMM) was put in place to support the cease-fire by patrolling the borders between Abkhazia, South Ossetia, and Georgia.
Given Ukraine's size and geo-strategic location, Moscow's 2014 intervention in eastern Ukraine and occupation and annexation of Crimea was a major escalation in terms of Russian use of force in Europe. Nonetheless, again, an analysis of the Ukraine conflict shows restraint being exercised by both Russia and the West and elements of cooperation between the two (Freedman, 2019). Russia limited its military intervention to eastern Ukraine and Crimea, despite fears by some in the West that it might seek to extend its intervention along the whole of Ukraine's Black Sea coast to link up with Russian forces already deployed in the Transdniestria region of Moldova or even to advance into western Ukraine and attempt to impose a Russia-friendly regime on the country (Marten, 2015). Likewise, the West refrained from intervening militarily in support of Ukraine, limited the armaments it supplied to Ukraine and has remained wary of rapidly advancing possible Ukrainian membership of NATO (Richter, 2014). In 2018-2019, the Trump administration expanded US military assistance and arms sales to Ukraine, including Javelin anti-tank missiles. Nonetheless, the overall scale of Western military assistance to Ukraine has been limited. Germany and France also joined with Russia and Ukraine in the socalled Normandy format, which helped to negotiate ceasefires which (even if not fully observed) have contained the conflict since 2015 and has provided a framework, albeit intermittent, for continued efforts to resolve the conflict (de Galbert, 2015).
Moscow's deployment of aircraft to Syria from 2015 and airstrikes against forces opposing the Assad regime constituted a further escalation of Russian military activity. In addition, since the United States and other Western states were also undertaking airstrikes against Islamic State and had forces deployed on the ground in Syria, Russian involvement in Syria raised the possibility of either side's airstrikes hitting the other's forces on the ground or of mid-air incidents or collisions between Western and Russian forces. In response to these risks, in 2015, the United States and Russia established a de-confliction mechanism, involving communication channels and advance exchanges of information. The de-confliction mechanism is viewed by both officials involved and external analysts as having successfully reduced the risk of direct Russian-US conflict in Syria (Bird et al., 2018;Weiss and Ng, 2019).
Overall, the record of these five crises suggests clear conclusions: restraint by both Western states and Russia in how they have used force and how they have responded to use of force by the other; a strong awareness of the risks of escalation and the need to take steps to avoid escalation (during the Georgia war, for example, the US administration explicitly considered the use of force and rejected it due to the risk of a direct US-Russia war -Asmus, 2010: 177-178 and 186-188); and, even in the midst of very significant disagreements, efforts to find and use inclusive political formats involving the West and Russia to address the conflicts. Whether such restraint arises primarily from calculations of self-interest or reflects some implicitly agreed rules or norms can be debated, but in either case, the restraint is real and important. Russia's interventions in Georgia, Ukraine, and Syria do indicate a greater willingness by Moscow to use force compared to the 1990s and early 2000s, which is sometimes interpreted in the West as a more risk prone approach. According to Eugene Rumer (2019: 1), however, Russian behaviour 'has been anything but reckless. Russian uses of hybrid warfare and military power -against Georgia in 2008 and Ukraine since 2014, as well as in Syria since 2015 -have been calibrated to avoid undue risks'.

Conclusion
An overall assessment of the risk of war between Russia and the West in Europe today presents a mixed, even contradictory, picture. Following the end of the Cold War, the immediate risk of war between Russia and the West declined dramatically in the 1990s. The contested nature of contemporary European order, especially in Central and Eastern Europe and the former Soviet region, however, created an on-going source of conflict. Since the late 2000s and accelerating since the 2014 Ukraine conflict, Russia and NATO have intensified their planning for possible war with one another, generating an actionreaction cycle, as well as military incidents (in particular in the air and seas). The breakdown of the previous informal rule against interference in each other's domestic politics has added to mutual tensions. Taken together, these developments have reinforced mistrust and elements of worst-case thinking in assessing the other side's actions and motivations. In these circumstances, war between Russia and the West is conceivable in a way that was not the case in the 1990s or 2000s.
Balanced against this, however, are a range of factors, which exist to some extent below the surface of day-to-day diplomacy but militate against war, arguably powerfully so. The contemporary European balance of power is best understood in terms of modified bipolarity, simplifying alliance choices and crisis management in Europe and providing an element of general deterrence vis-à-vis Russia. Despite the post-Cold War reduction and withdrawal of tactical nuclear weapons, the risk that any conflict between Russia and the West could escalate to nuclear war likely continues to have an important pacifying effect. Russia's energy supplies to Europe are a significant element of economic interdependence: Russia's dependence on gas and oil income from Europe means that any prolonged conflict with NATO would risk the disruption of energy trade and very significant economic costs for Russia. The destructiveness of a prolonged conventional war likely continues to impose caution on Western and Russian leaders. The post-1945 reconnaissance revolution continues to provide an important degree of transparency, helping to reduce the risk of surprise attack or pre-emptive war (the United States and subsequent Russian withdrawal from the Open Skies treaty in 2020-2021 may be viewed as a set-back in terms of military transparency, but does not undermine the larger element of transparency provided by reconnaissance satellites). Western and Russian crisis behaviour since the end of the Cold War, further, suggests that both sides have behaved with restraint, that they have worked to establish communication and, to some extent, cooperation, and that awareness of the risks and consequences of a Russo-Western war has made leaders relatively cautious in their decisions.
It is also worth reflecting on the nature of any potential war between Russia and the West. Gaddis' original long peace argument focused on prolonged war between the superpowers -a possible 'third world war' (Gaddis, 1986: 100). What, however, of the possibility of a more limited war between Russia and the West? The most likely trigger point of a war between Russia and the West is generally viewed as the Baltic states, which have been members of NATO since 2004 and are thus covered by the alliance's Article V security guarantee. Most Western analysts argue that, given the small size of the Baltic states and their geo-strategic position, under current circumstances, Russia could defeat and militarily occupy them within a few days (Shlapak and Johnson, 2016). Although NATO has since the 2014 Ukraine conflict put in place new plans to defend the Baltic states, including three multinational battlegroups of approximately 1000-1500 troops deployed in Estonia, Latvia, and Lithuania, critics argue that these are not sufficient to defeat a Russian invasion (Shlapak and Johnson, 2016). In these circumstances, Russia could invade the Baltic states and present NATO with a fait accompli, with NATO then having to risk a prolonged ground war -and significant wider escalation -to liberate the Baltic states or accept the new status quo (Shirreff, 2016). In such a scenario, it is possible to envisage a war between NATO and Russia remaining limited to the Baltic states, rather than escalating to a wider or more prolonged war. Nonetheless, were war to break out over the Baltic states, escalation dynamics could easily come into play, with both NATO and Russia facing military incentives to attack targets beyond the Baltic states, leading to a significant widening of any war (Colby and Solomon, 2015). The deployment of NATO forces in the Baltic states since 2014 (sometimes described as tripwire forces), further, increases the likelihood of any war escalating beyond the Baltic states. At minimum, Russia's leaders cannot be highly confident that any war would remain limited to the Baltic states and, if there is a risk of such escalation, then the wider structural dynamics discussed in this article are likely to shape decision-making in both Moscow and Western capitals. An additional possibility is of a hybrid attack (as in Ukraine in 2014) involving some combination of proxy or non-official Russian forces, disinformation and cyber war. While such an attack might allow Russia to gain control of Russian majority areas of Estonia and Latvia, however, it would be difficult for Russia to invade the entirety of the Baltic states by these means. Even in this scenario, Russian leaders would have to consider the possibility of a NATO military response and wider escalation, again bringing into play the larger structural factors discussed earlier. In this sense, the situation of the Baltic states today is analogous to that of West Berlin during the Cold War.
Russo-Western relations are undoubtedly at their worst since the end of the Cold War, with an action-reaction cycle of military planning and military incidents in the air and at sea. Significant increases in Russian forces deployed near Ukraine's eastern border in spring 2021 illustrated the risk of further crises with the potential for escalation to wider conflict. Balanced against this, nuclear weapons, the destructiveness of any prolonged conventional war, the structure of the balance of power, the reconnaissance revolution, and energy interdependence are powerful bulwarks against war. Russian and Western behaviour in crises since the end of the Cold War appears to reflect this logic. In assessing this debate, one can think in terms of the relative importance of structural factors (nuclear weapons, the balance of power, and so on) versus the political choices (or agency) of leaders. Unless one takes a deterministic view of the impact of structures, both are presumably important and shape developments. While the risk of war between Russia and the West is probably not as high as some alarmist warnings suggest, it is nonetheless real and has increased since the 1990s and early 2000s. Leaders and policy-makers in Western capitals and Moscow should therefore continue to behave with restraint, should maintain and further develop communication channels and confidence-building measures that help to prevent crises escalating and should explore possible rules of the game, whether formal or informal, they may help to stabilise the Western-Russian relationship. The February 2021 US-Russian agreement to extend the 2010 New Strategic Arms Reduction Treaty (New START) for 5 years can be viewed as a welcome step in this context.
The structural factors identified in this article suggest that, despite the downturn in Russo-Western relations, one can be cautiously optimistic that the long peace in Europe will continue. In the context of Russia's expansion of forces deployed near Ukraine in spring 2021, reports suggested that Russia was nonetheless behaving carefully and that the Biden administration was cautious in considering its response (Cooper and Barnes, 2021), arguably reflecting the structural dynamics discussed in this article. Nonetheless, as Gaddis (1991: 50) argued, the behaviour of leaders can make a 'critical difference' and peace also depends on the elusive qualities of statespersonship such as 'patience, courage, common sense, vision and humility'.

Funding
The author received no financial support for the research, authorship, and/or publication of this article.