Does the Balkans Need New Military Alliances?

Historical Background

The Balkan Peninsula has a long and complex history of shifting military alliances and foreign interventions. Early 20th-century pacts like the Balkan League, though formed to resist imperial domination, ultimately helped ignite successive wars. During the Cold War, the region’s fragmentation among NATO members, Warsaw Pact states, and non-aligned Yugoslavia placed continual pressure on smaller nations and set the stage for future instability.

In the 1990s, the breakup of Yugoslavia saw ad-hoc alliances between Balkan actors and external powers fueling polarization and conflict. History shows that when Balkan states pursued exclusive military pacts outside broader, inclusive frameworks, the result was often a security dilemma, heightening threats and escalating tensions rather than resolving them.

Post-war stabilization efforts rightly emphasized integration into structures like NATO and the EU. However, these efforts often overlooked the legitimate security concerns of states like Serbia, which has maintained military neutrality as a stabilizing factor. As one regional analyst noted, it was promising that Balkan countries had largely aligned along a Euro-Atlantic path — "the first time in history they were all on the same path" — but warned that recent moves to form selective military blocs, excluding key actors like Serbia, risk creating "new divisions and new confrontations."

Kosovo–Albania–Croatia Alliance

In March 2025, Kosovo, Albania, and Croatia formed a new trilateral security alliance – a notable development given the region’s delicate balance. On March 18, 2025, the defense ministers of Albania, Croatia, and Kosovo signed a joint declaration in Tirana pledging enhanced security cooperation. This “completely natural tripartite alliance,” as Albania’s defense minister described it, is essentially a memorandum of defense coordination rather than a full-fledged treaty. It was born of mounting security concerns shared by the three countries. Each member faced preceding threats that set the context for this pact:

• Kosovo: As a young actor with limited security capacities, Kosovo continues to face periodic instability, particularly in its Serb-majority northern regions, where political tensions and ethnic divisions remain unresolved. Despite efforts to strengthen local institutions, the fragile security environment regularly tests the ability of domestic forces to respond effectively. NATO’s Kosovo Force (KFOR) maintains a critical presence in ensuring stability and preventing escalation, underscoring that Kosovo’s long-term security still depends significantly on international peacekeeping arrangements and external guarantees. This reliance reflects broader challenges in the normalization process and highlights the need for renewed diplomatic engagement.

  
  

• Albania: As a NATO member, Albania has not faced direct military threats in recent years but sees instability in Kosovo as a national security concern. Incidents like the Banjska attack and the earlier (May 2023) mob violence against KFOR raised fears in Tirana of broader regional unrest. Albania, sharing deep ethnic ties with Kosovo Albanians, sought to solidify its influence and position through this new pact.

  
  

• Croatia: Croatia, an EU and NATO member, remains wary of Serbia’s regional role, recalling its conflicts from the 1990s. Watching Serbia modernize its military with acquisitions from Russia, China, and France has stirred concerns in Zagreb about the regional balance of power. Croatia thus aligned with Albania and Kosovo to present a common front, reinforcing deterrence toward Serbia, which they increasingly view as a geopolitical rival.

The Banjska incident has been widely cited as a catalyst for the Kosovo–Albania–Croatia alliance. However, the narrative remains contested. While Priština and Tirana portray it as proof of Kosovo’s vulnerability, Belgrade firmly rejected such accusations, calling for a full and impartial investigation before making political conclusions. Rather than serving as a neutral security measure, the alliance carries political aims of isolating Serbia, the key regional actor. Although framed defensively, it institutionalizes division. Serbia rightly protested, highlighting that the pact was formed without dialogue and involves a "structure that lacks international legitimacy" — Kosovo, whose independence remains disputed by nearly half of UN members and five EU states. Even former US National Security Advisor John Bolton warned that creating exclusionary alliances risks being "a real step backward" compared to NATO’s inclusive framework. Ultimately, the Kosovo-Albania-Croatia alliance risks destabilizing the Balkans by undermining NATO’s neutrality and marginalizing Serbia. No stable security architecture can exist without Serbia’s full and respected participation.

Serbia–Hungary Alliance as a Response

Belgrade did not sit idly in the face of the new trilateral alignment. Feeling isolated and threatened, Serbia moved to bolster its alliances. On April 1, 2025, Serbia and neighboring Hungary signed an ambitious defense cooperation agreement in Belgrade, elevating their military ties. This deal built upon a growing Serbia–Hungary rapprochement over recent years. Hungary’s Prime Minister Viktor Orbán and Serbia’s President Aleksandar Vučić have cultivated a close relationship grounded in both ideology and pragmatism. Orbán, known for his nationalist and pro-sovereignty stances within the EU, has been one of the few EU leaders openly sympathetic to Serbia’s positions, from delaying EU sanctions on Serbia’s partner Russia to expressing understanding of Belgrade’s refusal to recognize Kosovo. Conversely, Vučić values Orbán’s support on the European stage and Hungary’s willingness to engage with Serbia as a partner rather than a pariah. This political convergence set the stage for what some in Belgrade enthusiastically (unofficially) dubbed a “Hungary–Serbia alliance.”

The April 2025 agreement is officially a Defense Cooperation Plan for 2025, outlining concrete steps: 79 joint military activities, including exercises, arms industry cooperation, and officer training exchanges. President Vučić went so far as to herald it as effectively a “military alliance”. While no mutual defense clause was announced, the symbolism was powerful. For Serbia, which maintains a policy of military neutrality, this marked the first formalized military partnership with a NATO member state. It was a clear response to the perceived encirclement by hostile neighbors. Surrounded almost entirely by NATO countries (Croatia, Montenegro, North Macedonia, Bulgaria, Romania, Hungary) – several of which are now cooperating with Kosovo – Serbia felt strategically cornered. Serbian media and officials portrayed the pact with Hungary as a necessary counter-move to “NATO-aligned countries” forming blocs that exclude Serbia. Belgrade’s narrative is that the Tirana trio aimed to isolate Serbia; therefore, Serbia had to secure at least one reliable friend. In a pointed statement, the Serbian Foreign Ministry argued the Kosovo–Albania–Croatia pact was designed to isolate Serbia and even create threatening paramilitary structures, thus justifying Belgrade’s search for allies.

Hungary’s growing military and political cooperation with Serbia is an unusual and controversial move for a country that is both an EU and NATO member. The partnership, which deepened through a 2023 strategic agreement, has been framed by Prime Minister Viktor Orbán’s government as a step toward fostering regional stability and supporting Central European neighbors. At the signing, Hungary’s defense minister emphasized the need for frequent high-level consultations with Serbia to promote stability. However, this cooperation puts Hungary at odds with some NATO allies, as it positions itself as Serbia’s advocate within NATO and EU institutions.

Orbán’s approach reflects his broader strategy of pursuing “strategic autonomy” and cultivating ties with non-Western or semi-aligned states to assert Hungary’s independence in foreign policy. Serbia, with its close relationships with Russia and China, fits this mold. Orbán has also backed controversial figures such as Bosnian Serb leader Milorad Dodik, defying EU consensus. Thus, Hungary’s alignment with Serbia is seen by many analysts as a political signal rather than a purely defense agreement.

The Serbia–Hungary alliance primarily underscores Serbia’s and Hungary’s growing strategic isolation. With Russia preoccupied and geographically distant, and China offering limited direct support in a Balkan crisis, Serbia finds itself surrounded by increasingly NATO-aligned neighbors, except for Republika Srpska in Bosnia. On the other hand, Hungary is also growing more isolated and perceived as an unconstructive actor by the other EU countries. Both countries being in similar positions in this context, they offer each other a crucial, though limited, diplomatic and security partnership. The alliance allows for joint military exercises and defense industry cooperation, signaling that Serbia and Hungary are not entirely without allies.

However, the durability and depth of this partnership are constrained. Hungary remains a NATO member, and its military would ultimately prioritize alliance obligations over bilateral commitments with Serbia, making Hungarian military intervention on Serbia’s behalf against a NATO member improbable. Additionally, the relationship between Orbán and Vučić is heavily personality-driven, and a leadership change in either country could weaken the ties.

Ultimately, Serbia’s pivot to Hungary reflects its regional isolation more than a genuine strategic realignment. Analysts warn that recent moves like the Tirana trio (Albania, North Macedonia, Kosovo) and this Belgrade-Budapest pact could deepen regional fragmentation, potentially setting the stage for future conflict if not carefully managed.

Military Strength Comparison

Strategic Implications: Serbia–Hungary outmatch the Albania–Croatia–Kosovo bloc in conventional force metrics. However, the latter operates within NATO’s integrated architecture, benefiting from political and logistical support that the Serbia–Hungary axis lacks. Thus, while Serbia’s bilateral strength is superior, the broader NATO-aligned ecosystem still shapes regional power dynamics.

Did NATO Disappear?

The emergence of mini-alliances like the Kosovo–Albania–Croatia trilateral pact and the Serbia–Hungary axis has raised questions about the perceived reliability of NATO in the Western Balkans. Though NATO remains the dominant military force in Europe, with over 1.5 million active troops among its European members alone and hundreds of modern aircraft, these local initiatives suggest growing concerns among Balkan states about the Alliance’s political will to act in localized crises.

NATO continues to maintain a direct presence in the region: approximately 3,700 NATO troops operate as peacekeepers in Kosovo under KFOR, and around 1,100 EUFOR troops (backed by NATO) are deployed in Bosnia under a UN mandate. However, Kosovo, as a non-NATO member, lacks the protection of Article 5, leading its leaders to worry about NATO's ability to respond quickly to potential hybrid threats.

Albania and Croatia, though NATO members, also fear that NATO’s strategic attention is fixed more on Russia and the eastern flank, not the Balkans. Their trilateral pact can be seen as both a message to Belgrade and a subtle critique of Brussels and Washington. One Albanian analyst said these alliances are not just military deals, but about “survival in unpredictable times,” reflecting doubts about external guarantees.

Though France alone has more combat aircraft and professional troops than all Western Balkan militaries combined, it's not NATO's raw capability that’s in question, but its focus and credibility. Former US National Security Advisor John Bolton criticized the trilateral pact as duplicating NATO structures, suggesting it indicates discontent with the current Alliance posture.

This growing trend poses strategic risks. European diplomats have warned that creating parallel security structures could erode NATO’s role. NATO’s Secretary General at the time, Jens Stoltenberg, emphasized that although such alliances are outside NATO’s mandate, the Alliance remains the bedrock of regional security.

The EU’s long-stalled enlargement is also part of the problem. Balkan candidate countries have grown impatient with Brussels’ delays, which have pushed them to seek alternatives. One former ambassador argued that EU indecision “created the fragmentation we’re seeing now”.

These new regional alliances are not a sign that NATO has disappeared, but that its guarantees are perceived as incomplete in some contexts. The solution lies not in dismantling NATO’s role but in reassuring allies, speeding up EU integration, and ensuring NATO remains credible and responsive to local crises.

Mini Cold War in the Balkans and Threats to Regional EU Integration

It is not unreasonable to say that the Western Balkans is entering a “mini Cold War”, marked by the emergence of two rival camps. One alignment includes NATO members such as Croatia, Albania, and Kosovo, while the other centers around Serbia, with Hungary emerging as a prominent supporter. This divide risks reviving the Cold War logic of regional bifurcation, only now with EU and NATO members like Hungary and Croatia on opposing sides, undermining the EU’s unity and foreign policy coherence.

The two primary flashpoints, Kosovo and Bosnia, highlight this fragmentation. In Kosovo, the EU-backed government faces off with Serbia, which enjoys Russian and Hungarian support. In Bosnia and Herzegovina, Republika Srpska, under Milorad Dodik, continues to defy the central government and the international High Representative, emboldened by backing from Serbia, Russia, and Hungary. A pivotal moment came in March 2025, when Dodik was convicted of violating the constitutional order. Hungarian PM Viktor Orbán condemned the verdict, while Croatia’s PM Andrej Plenković defended legal norms, symbolizing how the rift has penetrated EU unity.

Although modernizing defense capabilities is not inherently destabilizing, the creation of exclusive military alliances creates a security dilemma. As analyst Risto Nikovski warned, the Albania–Kosovo–Croatia pact "became a signal of regrouping" that Serbia interpreted as a threat, prompting its alignment with Hungary. Now both sides are rearming, notably with Rafale jets, drones, and tanks, and conducting military exercises that deepen mistrust.

This climate also risks derailing EU integration. The EU’s strategy for the Balkans, embodied in the Berlin Process and the Common Regional Market, relies on regional cooperation. But the new Cold War atmosphere hardens positions. Serbia and Kosovo, for instance, may be less inclined to compromise in the EU-led dialogue, as they now feel emboldened by their respective blocs. Similarly, Hungary’s overt support for Dodik undermines the Dayton Peace Agreement and weakens international oversight in Bosnia.

The credibility of the EU as a neutral arbiter is further eroded when member states openly back opposing sides. For Serbia, this confirms the belief that "Brussels will again pay the price" for internal division. Meanwhile, Kosovo and Albania may lose faith in EU mechanisms due to Hungarian vetoes and softness toward Belgrade. This dynamic harms the EU's enlargement agenda, which requires regional good-neighborly relations, already fragile, as shown in North Macedonia’s delays over the Bulgaria dispute.

Even neutral countries are feeling the pressure. North Macedonia, a NATO member with a large ethnic Albanian population, risks internal instability. If Albania’s bloc expands to include Bulgaria, Skopje could find itself squeezed between ethnic solidarity and geopolitical pressure. Montenegro, also in NATO since 2017, faces a similar dilemma. Deep internal divisions, reflected in the latest census, where 41% identified as Montenegrin and 33% as Serb, have destabilized its politics. The current pro-Serb coalition government could tilt Montenegro toward Serbia's camp, alarming the pro-Western factions and NATO.

This fragmentation threatens EU cohesion as well. If Croatia and Hungary back opposing Balkan partners, EU foreign policy loses credibility. Russian media would certainly capitalize on this, framing the Balkans as an example of EU disunity and Western hypocrisy.  Inside the EU, such divergences strain Council decisions. Hungary has repeatedly watered down EU statements on Serbia and the Republic of Srpska, eroding Brussels’ leverage.

Consequences

The Western Balkans are increasingly fragmenting into opposing military blocs, undermining regional unity at a critical time. Countries like Bosnia and Herzegovina, North Macedonia, and Montenegro, aspiring EU members, are now caught in a climate of growing mistrust and exclusion. At the center of any long-term solution is Serbia, whose demographic and strategic weight make its inclusion essential. Frameworks that isolate or target Serbia risk prolonging instability; instead, Serbia should be integrated into a new, inclusive regional security architecture, potentially a neutral, non-NATO-aligned platform focused on dialogue and shared threats.

The rise of the Kosovo–Albania–Croatia alliance and the Serbia–Hungary axis, though driven by valid concerns, may lead to a “two fires” scenario, with Bosnia and Kosovo as potential flashpoints. If these rival blocs deepen, they risk triggering a Balkan mini–cold war, even involving EU and NATO states on opposite sides.

To prevent this, the region needs de-escalation, renewed Euro-Atlantic commitment, and inclusive security frameworks. The EU must also reassert its enlargement vision to prevent further fragmentation and to uphold peace, stability, and regional integration.

Recommendations for Policy Makers

• Learn from history and don’t let it repeat itself: Balkan history teaches that exclusive military pacts and rival alignments often precede instability, not peace. From the Balkan Wars to the 1990s conflicts, every instance of fragmented security structures has led to a deepening of mistrust and eventual escalation. Policymakers should resist the temptation to form alliances that signal confrontation rather than cooperation. Strategic patience and restraint are required to avoid a security dilemma that destabilizes the region. A multilateral approach, anchored in dialogue and inclusivity, should be prioritized over bloc-building.

  
  

• Acknowledge the unconstructiveness of parallel military structures: The creation of parallel alliances such as the Kosovo–Albania–Croatia pact or the Serbia–Hungary alignment weakens the region’s collective security architecture and undermines NATO’s integrative logic. These structures duplicate existing frameworks, confuse military command channels, and signal a lack of trust in current institutions. Policymakers should avoid endorsing initiatives that bypass NATO or EU processes and instead work toward enhancing coordination within existing multilateral platforms. Unilateral moves may offer short-term reassurance but breed long-term fragmentation.

  
  

• Escape the “Prisoner’s dilemma” scenario: Each side in the region now acts based on the assumption that the other is preparing for confrontation, prompting preemptive alignment and rearmament. This logic, similar to the “prisoner’s dilemma,” leads to mutual distrust and militarization. To break this cycle, leaders must shift the strategic narrative from zero-sum balancing to cooperative security. Confidence-building measures, military transparency, and region-wide de-escalation protocols should be implemented to reduce threat perceptions. The cost of miscalculation in the Balkans is too high to ignore.

  
  

• Restore trust in NATO security structure: While NATO remains the cornerstone of European security, perceptions of its declining responsiveness in the Western Balkans are fueling alternative alliances. The Alliance must reaffirm its commitment to regional stability by increasing its political visibility, reviewing its posture in the Western Balkans, and ensuring that members like Albania and Croatia feel heard and protected. NATO should also explore creative solutions to involve Serbia in cooperative security measures without pressuring it toward membership, thereby maintaining NATO’s credibility, Serbia’s military neutrality, and relevance across the region.

  
  

• Inclusive security framework: A stable Balkans cannot be built on exclusion. Serbia, due to its size, geography, and political influence, must be part of any viable long-term regional security solution. A neutral, non-aligned security forum, possibly under EU or OSCE auspices, should be explored to complement NATO and include all Western Balkan states regardless of alliance status. This forum could focus on shared concerns like border security, hybrid threats, disaster response, and arms transparency. Inclusiveness, not polarization, must be the foundation of any future security architecture in the region.

  
  

• Firmly support regional economic initiatives: The US and EU should prioritize and actively support regional economic cooperation frameworks that foster stability, connectivity, and interdependence in Southeast Europe. Initiatives like Open Balkan, despite past political skepticism, represent pragmatic, bottom-up models for advancing labor mobility, trade integration, and depoliticized collaboration. Rather than viewing such efforts through the narrow lens of conditionality or competition with EU enlargement, Washington should recognize their potential as complementary confidence-building platforms that can prepare the ground for future accession. In this regard, a revised transatlantic approach should offer technical assistance, promote regional ownership, and emphasize practical deliverables. Additionally, frameworks like the Three Seas Initiative, focused on infrastructure, digitalization, and energy diversification, could serve as valuable models for integrating Western Balkan states into broader Euro-Atlantic economic and strategic networks, especially when adapted to regional realities and capacities.

Date:
May 21, 2025

Authors:
Vuk Velebit, Pupin Initiative
Andrej Cvejanov, Pupin Initiative

Researchers:
Petar Ivić, Pupin Initiative
Aleksa Jovanović, Pupin Initative