Greeks wave their national flag. (Petros Giannakouris/AP)

As the threat of GREXIT looms, it is fair to ask what, if any, consequences such an event would have for Greece’s security.  In recent statements published in the news daily Kathimerini, European Commissioner Dimitris Avramopoulos said Greece’s remaining in the euro zone constitutes a security guarantee. That message, which was also conveyed by Prime Minister Alexis Tsipras in recent statements, was given in the context of a conversation about the security implications of the illegal immigration problem in Greece. Rising numbers of illegal and undocumented migrants with ethno-religious differences from the generally homogenous Greek population is a problem that has been used successfully as a mobilization device by parties nursed by extreme ideological positions. Popular Orthodox Rally (LAOS) leader Giorgos Karatzaferis skillfully brought the issue to the forefront of political debates in the country in early 2000s, and the neo-fascist party Golden Dawn built its electoral success on extremist anti-immigrant rhetoric.

However, the security implications of the immigration issue are a side show compared with Greece’s long-standing security concerns emanating from its enduring rivalry with Turkey, made more complicated by the ongoing sectarian conflict in the Middle East. During an intense period of Eurogroup negotiations over Greek debt in early March, Turkish provocations in the Aegean taking the form of incursions in Greek airspace reminded the Greek public that the Near East could be an unfriendly place.  The subtext of news articles covering these events in the context of debt negotiations was clear: European Union (E.U.) guarantees are important not only to support Greece’s economy, but also to shield Greece from the Turkish threat.

The most likely consequence of GREXIT, Greece’s leaving the euro, would be permanent exclusion of Greece from the euro zone, while the country remains in the European Union. However, many in Greece fear the worst – that defaulting on debt owed to European taxpayers would somehow land Greece outside the union. That extreme scenario is what generates real concern over security (merely leaving the euro zone should have much milder security implications than any considered below). We will, therefore, consider the extreme case. Greece would have no friends in Europe on whom it could count for its defense.

We will assume that Greece’s primary security threats stem from Turkey’s revisionism in the Aegean Sea and in Cyprus and from Turkey’s broader aspirations for a hegemonic position in the Near East. Greek foreign policy has been defined by regional competition with Turkey. We will summarize our view of Turkey’s main strategic interests and explain how these are likely to change in the event of GREXIT. We will not consider the effects that GREXIT might have on broader European security, though that is an interesting question that might be usefully analyzed.

To preview what follows, we do not expect GREXIT to have significant security implications for Greece.

There is no precedent for Greece’s current predicament in Europe, so we cannot rely on the empirical record to make predictions. Instead, we postulate some answers by drawing on the major theories of International Relations (IR).

Let’s start with structural realism — the dominant theory of IR. Realism assumes that states can be considered as unitary actors competing in an anarchic, self-help system to ensure their survival and, if possible, increase their power. If Greece leaves the European Union, this might diminish European interest to preserve peace and security in the Aegean Sea since Greece’s external borders would no longer be Europe’s borders.

However, a new European strategy under development considers a seamless security environment that engulfs the Mediterranean and extends far beyond the Suez Canal and the Black Sea, which would suggest continued interest in preserving peace in the Aegean. More importantly, Greece would still be a member of NATO. Given that Europe does not have an army or a coherent security policy, losing the option of direct security assistance from Europe would amount to a negligible loss.

Is NATO membership a sufficient guarantee of Greece’s security? In general, many IR scholars argue that small states gain something by joining alliances because they deter aggression from challengers.  But the effect of alliances on war can be ambiguous. According to rational choice theories of world politics, alliance formation is a foreign policy tool of major powers designed to serve their own national interests. They pay a lot for them because they’re good for them. From that perspective, alliances might not be worth more than the paper that they are written on. If the balance of power changes in a way that alters the security interests of the dominant power, then its commitments to its alliance partners can also change. Applied to Greece, that logic suggests that GREXIT should not generate much concern: NATO’s vital interests — which many would argue are nearly synonymous to American national security interests — would not be directly threatened by GREXIT, so there is little reason to expect a weakening of NATO’s commitment to Greece, other things held equal.

Moreover, NATO is not about Greece. With or without GREXIT, NATO commitments to Greece are questionable. The alliance has always been about the U.S./Russia relationship. Given American security interests in the Middle East, Turkey is a more important ally for the United States, and the history of Greek-Turkish relations offers a unique lesson. A prior military confrontation between these two NATO allies was allowed to escalate to a brief war in Cyprus that effectively changed European borders in 1974.

That said, Greece’s geopolitical importance in the region is not trivial. The military base in Souda Bay (in the island of Crete) is used heavily by the U.S.-NATO air force. Furthermore, the discovery of hydrocarbons in the eastern Mediterranean has complicated the security matrix and should push the United States to maintain the status quo in the Aegean. The U.S.-Turkey relationship is tense, and the rise of Islamism in Turkey creates uncertainties in light of which, the United States and NATO should want to preserve a positive relationship with Greece.

Overall, both theory and history in this case suggest that Greece cannot entirely trust NATO’s commitment to defend its territorial integrity in case of a military confrontation with Turkey. This is reflected in Greece’s outsize military expenditures, which suggest that the security guarantees offered by NATO (there were none offered by the E.U.) were never seen as entirely credible. Military expenditures have not fluctuated in a way suggesting any deterrent effect due to E.U. membership, and the decline in the length of military service was also unrelated to the perception that Europe had Greece’s back (it was driven more by budgetary questions and the modernization of the military).

Thus, while there is reason to doubt the extent of NATO’s commitment to Greece, GREXIT is unlikely to weaken that commitment. Some realists would go as far as to doubt most institutional guarantees of any country’s security. So from the perspective of structural realist theory, GREXIT should not have direct negative implications on Greece’s alliance relations or overall security environment other than creating some small measure of uncertainty about a now more volatile strategic zone for NATO.

Might the possibility of an alliance with Russia change that conclusion? Faced with the prospect of running out of cash to pay pensions and salaries, Tsipras traveled to Russia recently in a diplomatic overture intended to threaten his European interlocutors with the prospect of a Greek realignment toward Russia. Russian expansionism in the broader Eurasian region benefits from recent tensions in the Greece-E.U. relationship. Would an alliance between Greece and Russia change the security status quo in the region?

We think that such an alliance is unlikely to occur as Russia’s own economic problems aggravated by the decline in the price of oil — would prevent it from offering significant assistance to Greece. There is some support among the Greek public for a turn to Russia, but it’s not overwhelming. But even if there was an alliance, it would be hampered by the lack of direct geographical access between the two countries and by interoperability issues (Russian assistance would take too long to have an effect given how long Greece has been a member of NATO). At the margins, the threat of a Greek realignment could provide an incentive to both the United States and the E.U. to continue offering security guarantees to Greece even in the event of GREXIT. But a realignment is not going to happen.

In contrast to the structural realist theory, which assumes that security is paramount, different theories of international relations notably liberal internationalism and constructivism make assumptions about state preferences that allow predictions of more international cooperation. There are varieties of these theories, some of which share key elements of realism (such as the primacy of state’s concern for survival). The further away they move from realism, the more they are likely to acknowledge an independent effect of institutions on state behavior.

Such theories, organized under the umbrella of neoliberal institutionalism, typically explain the formation of institutions such as the United Nations or the Bretton Woods financial institutions as outgrowths of American hegemony. After winning a hegemonic war, the victorious power needs to establish a system that enables it to maintain order at the lowest cost. Institutions encode rules of behavior and help establish hierarchical relationships with smaller states, which can enjoy order in exchange for deference. These institutions generate some measure of legitimacy that helps perpetuate world order and minimizes challenges to the hegemonic power. The more the major powers gain from these institutions and from the defensive alliances that support them — the more they will contribute to them. Their commitment to protect smaller states’ vital security interests will be a function of how costly it would be for the major powers to allow a change to the status quo.

Less power-centric versions of institutionalism focus on the origins of international institutions in inter-governmental bargaining on behalf of domestic interest groups and commercial interests. From an institutionalist perspective, Greek-Turkish relations should be shaped by, for example, the extent to which commercial interests between the two countries support peaceful relations; or by institutional constraints on aggression by the executive in either country; or by the mutual respect that ties together democratic regimes in a zone of peace. (This assumes that Turkey’s polity can be characterized as a democracy and that it will remain one despite the recent turn to Islamism; it also assumes that Greece is a consolidated democracy and would remain so after GREXIT).

GREXIT is unlikely to radically change any of the variables that would shape outcomes in an application of such theories to the case of Greco-Turkish conflict. A caveat is that GREXIT might empower ultra-right nationalist parties in Greece, in which case we could expect a ratcheting up of anti-Turkish rhetoric — not least as a diversionary tactic to unify the nation during a deepening economic crisis. The last serious conflict between the two countries took place during a period of military dictatorship in Greece. But for this to happen, Golden Dawn would have to hold the reins of Greek foreign policy, and current theorizing about the determinants of electoral success of radical parties suggests that Golden Dawn is unlikely to capture that level of power.

Neoliberal theory has surprisingly little to say about alliance politics. For the most part, all variants of neoliberal theory explain institutions as grounded in state interests. In turn, state interests are seen as arising from the aggregation of preferences of domestic interest groups. Though motives other than security drive many of these groups, security still matters. The standard account of the European community is one anchored in security: the European Defense Community in the 1950s and the institutions of the Common Market were built to ensure that the victors of World War II could tame Germany’s aggression by tying its fate with that of the rest of Europe. A different view of European institutions is that they were the result of inter-governmental bargaining over commercial interests.  And, once formed, European institutions developed some agenda-setting power of their own, shaping member-state interests, as European policy elites sometimes act in ways that are not entirely circumscribed by the interests of their home countries.

Seen from this perspective, GREXIT would generate a stronger negative reaction in Europe by angering policy elites and generating economic costs for politically important interest groups in powerful European countries. The prediction would, therefore, be that European alliance commitments to Greece would weaken. But even so, the negative reaction is unlikely to result in coercive action toward Greece.  Historical analyses of sovereign debt defaults suggest that the era of gunboat diplomacy has ended and the idea that states will utilize military force to recover their losses in case of sovereign debt default does not receive empirical support. Thus, a Greek default would not result in any direct security risks coming from Europe.

Conspiracy theorists in Greece might say that Turkey’s heightened aggression during the Eurogroup negotiations in early March was staged: NATO, the United States or some undefined actor might have somehow pushed Turkey to violate Greek airspace so as to frighten Greek voters and deter Greece from defaulting out of concern for the security implications of such a move. It would be hard to prove this, but the conspiracy theory is broadly consistent with how international institutions work.

A key mechanism explaining interstate cooperation according to neoliberal institutionalism is “issue linkage”: the fact that membership in multilateral institutions allows states to tie together their adversaries’ behavior across two or more issue areas so that they can threaten retaliation in one issue area if they do not get cooperation in another. Structuring tradeoffs across issue areas might allow politicians to reach agreement on difficult issues in other areas. But these tradeoffs can just as easily be used as threats: recall how American NGOs were pushing the U.S. government to threaten trade sanctions against China unless China agreed to improve its human rights record. Thus issue-linkage might predict that the prospect of GREXIT would generate cross-issue pressure on Greece not to default. However, if GREXIT does happen, there is nothing to suggest that these pressures would persist: Simply punishing Greece for a fait accompli is not consistent with issue linkage or other mechanisms underlying institutionalist theory.

Moving beyond realism and liberalism, the third major IR theory is constructivism.  According to constructivism, international anarchy need not always imply conflict because state interests and identities co-evolve over time as a result of inter-state interactions. So states might not perceive others as hostile, and they may internalize norms of international cooperation cultivated by multilateral institutions. How likely is the prospect of Turkish aggression from this perspective? Greece and Turkey have over time developed identities that are mutually hostile. There has been a gradual improvement of relations since the last militarized dispute over the Imia islands, in the 1990s, but our starting premise is that both Athens and Ankara view each other as a threat. How would this change in case of GREXIT?

GREXIT would constitute an abrupt and unexpected shift in the nature of Greece’s relationship with Europe and would define Greece’s economic and financial interests in opposition to European interests.  Yet, the experience of sharing a common market and a common currency and the process of building common political institutions over several decades in post-war Europe should have created a security community that includes Greece. Ultimately, success of the European project depends on the cultivation of a shared identity that dampens state nationalism in favor of joint investment in and identification with the inter-governmental conglomerate.

However, the continuing conflict over Greek debt has revealed that a strong European identity has not yet emerged. There is ample evidence of this, including the very public conflict between Germany and Greece, rife with mutual recriminations, escalating political demagoguery, and the stigmatization of national identities (the Germans are “Nazis”; the Greeks are “lazy”). One now questions whether there is sufficient solidarity among European nations to substantiate the constructivist assumption that state interests and identities co-evolve as a result of being linked together by institutions of alliance and commerce. If the European security community was more an abstract idea than reality, then not much would be lost in case of GREXIT. But even if the constructivist interpretation of the European project were right, then GREXIT could not interrupt cultural or political bonds that should have developed between Greeks and other Europeans over decades of shared experience. Thus, one way or another, constructivism would not predict major security consequences for Greece in case of GREXIT at least from the perspective of how it would affect relations between Greece and the rest of Europe (we consider the effect it would have on Turkey next).

Ultimately, the security risks that Greece faces going forward depend on what Turkey really wants. How does Turkey see its security interests in the Mediterranean and the broader Middle East region? Is it a status quo or revisionist power? Does it have ambitions to become a regional hegemon, and does Greece stand in the way?

Looking at Turkey’s strategic choices over the past two decades, we see a country grappling with developing a ‘grand strategy.’ Its hegemonic aspirations are reflected in earlier efforts to acquire a Landing Platform Dock that could be transformed into an aircraft carrier and nuclear plants with the capability of producing nuclear weapons. Turkey has recently initiated a large redesign of its military defence program so as to establish itself as a regional power. Given this, and Turkey’s persistent challenges to the territorial status quo in the Aegean and in Cyprus, we consider Turkey a revisionist power.

GREXIT would not affect Turkey’s underlying preferences according to security-focused theories such as structural realism, but perceived weakness in Greece might entice opportunistic challenges in pursuit of long-standing goals. Turkey would continue to project its assertions in the Aegean Sea and would try to maintain the status quo in Cyprus so as not to allow any changes in the balance of capabilities relative to a hostile neighbor (recent initiatives among Greece, Cyprus and Egypt to establish sea borders and exclusive economic zones for the exploitation of Mediterranean hydrocarbon reserves are a further stimulus for Turkey’s desire to preserve the status quo in Cyprus).

If the Greece-Europe nexus is broken, Turkey would be able to formulate a more coherent and forcible strategy against Greece. Realist self-help logic would have Turkey develop further its offensive military capabilities with the goal of promoting its economic, commercial and maritime rights over the exploitation of the natural and mineral wealth of the Aegean Sea. This would probably result in more Turkish aggression over the control of small islands in the wider Aegean archipelago with currently undefined ownership status. As a counterweight to this scenario, we should consider that Turkey’s open conflicts in Syria and Northern Iraq should diminish any appetite for opening a new conflict front with Greece. Similarly, its internal conflict with its Kurdish population should diminish interest in overseas adventurism. On balance, however, the structural realist view would be that the perception of threat from Turkey would grow as Greece’s military strength is adversely affected by GREXIT. That risk should be weighed against the military weakness already incurred in Greece as a result of the recession because of policies intended to avert GREXIT (defence expenditures have already been significantly curtailed because of an about 25 percent drop in GDP).

From the perspective of neoliberal institutionalism, the most important parameter to consider is Turkey’s aspiration to join the E.U. As long as that remains a goal of Turkish foreign policy, it should induce restraint vis-à-vis Greece regardless of GREXIT.  However, Turkey’s commitment to the goal of European membership is questionable. There are two main clues: First, Turkey is not really trying to comply with the acquis communautaire (the overall legal framework articulated in the E.U.), and, second, recent public opinion surveys show the Turkish public shifting away from the idea of E.U. accession despite some positive signs. The strict framework of conditionality, established by the Helsinki European Council in 1999 regarding Turkey’s E.U. candidacy no longer shapes Turkey’s security priorities in the Aegean conflict or in Cyprus — the two primary areas of focus in Greek-Turkish relations. Turkey will pursue a favorable resolution of outstanding issues with regard to the boundaries of territorial waters and the delimitation of the continental shelf and the use of exclusive economic zones as a priority.

Other issues also matter to it (e.g., narrowing Greek airspace; demilitarizing Greek islands close to the Turkish coast; and resolving the ownership status of ‘grey zones’ in the Aegean – geographic formations with undefined legal status). Turkey is less constrained in the pursuit of these policies by a withering desire to be in Europe. The new constitutional arrangements planned to be adopted by the followers of the ruling Justice and Development Party (AKP) in June and the suppression mechanisms with regard to the use of the social media or the rights of journalists point to a shift away from democratic norms and institutions, which should weaken further Turkey’s commitment to peace in the Aegean according to the theory of the democratic peace. Moreover, commercial interests, trade and nongovernmental relations between Turkey and Greece were never influential enough to shape policy choices. Thus, overall, according to neoliberal theory, the risks of intensifying conflict between Greece and Turkey are substantial. However, GREXIT per se would not be to blame.

What about constructivism? On the one hand, the claim would be that, over decades of engagement with Europe, there has been some sort of convergence of ideas and interests that have made Turkey less threatened by — and less threatening to — any European state. That said, both in the E.U. and Turkey there is a sense that the distance between European and Turkish identities is large, at least partly having to do with religious differences. Greek and Turkish identities are even further apart, the distance having been made salient by an enduring conflict. Constructivists would argue that a GREXIT scenario would undermine Greece’s diplomatic reach in Europe and gradually weaken the perception of Greece as part of the European security community. That, in turn, might embolden Turkey as it projects its revisionist claims in the Aegean and in Cyprus. Yet, as mentioned above, constructivist assumptions do not seem to accurately describe the level of European solidarity, so GREXIT would not exert pivotal influence on the future of Greek-Turkish relations.

To sum up, predicting the effects of GREXIT on Greece’s security requires recourse to theory — and theory depends on assumptions. We explored three main families of IR theories, each of which makes different assumptions about what states want. It is not possible to put realism, institutionalism and constructivism in a horse race against one another, and each theory could be usefully employed to illuminate different problems in world politics. For our question, on balance, theoretical predictions lean in the direction of discounting the effects of GREXIT on the future of Greek security. GREXIT, if it happens, will undoubtedly have major financial consequences both in Greece and in Europe and might even undermine the entire European edifice. But concerns over security should not complicate further Greece’s calculus over the costs and benefits of such a policy decision.

Nicholas Sambanis is a professor of political science at Yale University.  Ioannis Galariotis is post-doctoral research fellow at Athens University of Economics and Business.