The strategic manipulation of migratory flows for political and geopolitical objectives has emerged as one of the most consequential challenges to state sovereignty in the twenty first century. This phenomenon, increasingly recognised in international law and policy discourse as the instrumentalisation of migration, involves the deliberate orchestration or facilitation of irregular cross border movements by states or state affiliated actors to exert pressure on other states, extract concessions, or destabilise political systems. The weaponisation of human mobility represents a fundamental assault on the territorial integrity and border control prerogatives that constitute core attributes of sovereign statehood. The European Union and its member states have confronted this challenge with particular intensity, given the continent’s porous external borders, the Schengen area’s internal freedom of movement, and the proximity of unstable regions generating large migrant populations. Three distinct episodes illustrate the evolving sophistication of migration instrumentalisation: the Ceuta crises of 2021 and 2026, the broader European migration crisis of 2015, and the hybrid warfare campaigns conducted through Belarus and Turkey. Each case reveals different modalities of instrumentalisation, from diplomatic coercion to systematic hybrid warfare, yet all share a common objective of using human displacement as a lever to undermine the sovereignty of targeted states. Conceptual Framework: Instrumentalisation and Sovereignty The instrumentalisation of migration is defined under EU law as occurring when states or non state actors use migrants as a tool for political pressure with such intensity that it objectively puts essential state functions at risk. This definition captures the dual nature of the phenomenon: it is simultaneously a political strategy and a threat to governance capacity. The European Commission has explicitly characterised hybrid threats arising from the weaponisation of migration as posing a risk to the sovereignty, national security and territorial integrity of concerned member states. State sovereignty in the modern international system rests on several foundational pillars: territorial integrity, the monopoly over legitimate violence within borders, and the authority to regulate entry and exit across frontiers. The control of borders is arguably the most tangible expression of sovereign authority. When a state loses the capacity to determine who enters its territory and under what conditions, its sovereignty is materially diminished. Instrumentalisation exploits this vulnerability by overwhelming border management capacities through artificially generated surges. The strategic logic of instrumentalisation follows a consistent pattern. A state seeking to pressure another state relaxes its own border controls or actively facilitates the movement of migrants toward the target’s territory. The resulting humanitarian and administrative crisis forces the target state to either absorb the migrants, incurring social and economic costs, or engage in coercive pushbacks that generate international condemnation. In either case, the target state’s sovereign prerogatives are compromised. The instrumentalising state can then offer to restore cooperation in exchange for political or diplomatic concessions. What distinguishes instrumentalisation from ordinary irregular migration is the element of state direction or knowing facilitation. The migrants themselves may be unaware that they are being used as instruments of state policy. The instrumentalising state does not necessarily control the migrants' ultimate destinations, but it creates the conditions for mass crossings that it knows will overwhelm the target’s border control systems. This element of intentionality is crucial for understanding instrumentalisation as a deliberate assault on sovereignty rather than a merely unfortunate consequence of migratory pressures. The Ceuta Crises of 2021 and 2026: Moroccan Coercive Diplomacy The 2021 Ceuta Crisis The crisis that unfolded in Ceuta during May 2021 stands as a seminal example of migration instrumentalisation as diplomatic coercion. Ceuta, a Spanish autonomous city of approximately 80,000 people located on the northern coast of Africa, shares the European Union’s only land border with Morocco. This geographical vulnerability has rendered Ceuta a perennial flashpoint in Spanish Moroccan relations. The immediate trigger for the 2021 crisis was a diplomatic dispute over Western Sahara. Madrid had permitted Brahim Ghali, the leader of the Polisario Front which seeks independence for Western Sahara from Morocco, to receive medical treatment in a Spanish hospital. Morocco, which considers Western Sahara an integral part of its territory and views the Polisario Front as a separatist movement, interpreted this humanitarian gesture as a hostile act. The kingdom responded with a calculated demonstration of its capacity to generate migratory pressure. Between 17 and 18 May 2021, Moroccan border guards relaxed their controls, allowing approximately 8,000 to 12,000 people to cross into Ceuta. Video footage appeared to show Moroccan border guards waving migrants past their controls. The Spanish government characterised the incident not as a migratory crisis but as an attack on its borders, with officials describing the movement of migrants as an assault on the country’s territorial integrity. Prime Minister Pedro Sánchez declared that the situation represented a serious crisis for Spain and for Europe, and that his priority was to guarantee control of transit at the border with Morocco. Spain responded by deploying military forces to Ceuta, with the Comandancia General de Ceuta mobilising multiple units including the Regiment of Regulars, the Tercio Duque de Alba of the Legion, and engineering and artillery regiments. The government also approved 30 million euros in aid to Morocco for border policing. Approximately 4,000 to 6,500 migrants were returned to Morocco under readmission agreements. The diplomatic calculus underlying Morocco’s actions was transparent. By generating a sudden migratory surge, Morocco demonstrated its capacity to impose costs on Spain unless Madrid adjusted its Western Sahara policy. The crisis achieved its intended effect: Spain subsequently shifted its position on Western Sahara, abandoning neutrality and backing Morocco’s plan to grant the territory autonomy under Moroccan sovereignty. Morocco had successfully used migration as leverage to obtain a major diplomatic concession. The 2026 Ceuta Crisis The 2026 Ceuta crisis represented an escalation of the same instrumentalisation strategy, conducted on a vastly larger scale. On 30 July 2026, between 40,000 and 60,000 illegal migrants flooded into Ceuta from Morocco. The surge occurred in less than 24 hours, with migrants swimming around the border breakwater and breaching land barriers. The number of arrivals amounted to approximately 70 percent of Ceuta’s population of 83,600. At least 57 people died during the crossing, with many drowning in the attempt. Spanish authorities estimated that approximately 49,000 to 50,000 people had crossed the border. The influx overwhelmed local authorities, with only 55 border agents on the front line when the situation broke out, a force described as three or four times less than what would be needed to manage such an event. Prime Minister Sánchez rushed to Ceuta and characterised the mass crossing as a violation of Spain’s territorial integrity and an attack on Spanish sovereignty. He attributed the surge to trafficking mafias that had exploited a recent Supreme Court ruling restricting the immediate deportation of migrants intercepted at sea. However, Western intelligence sources suspected that Morocco had facilitated the sudden influx. The 2026 crisis occurred against a backdrop of renewed diplomatic tensions. Sánchez had recently visited Algeria in an exercise of diplomatic fence mending to soothe Algerian anger at Spain’s 2022 decision to support Morocco’s Western Sahara autonomy plan. This visit apparently angered Rabat, which responded by once again unleashing migratory pressure. The scale of the 2026 surge suggests that Morocco had refined its instrumentalisation capabilities, deploying them with greater intensity than in 2021. Italy responded by suspending the EU’s border free Schengen arrangements with Spain. France ordered extra checks along its Spanish border. The diplomatic fallout extended beyond Spain, affecting the entire Schengen area and demonstrating how migration instrumentalisation at one external border can destabilise the wider European free movement regime. The Spanish government ultimately repatriated most of the migrants, with more than 48,000 voluntarily returning to Morocco by the evening of 31 July. However, the episode exposed the fundamental vulnerability of states that share land borders with neighbours willing to weaponise migration. Spain’s sovereignty over Ceuta was directly challenged also by the implicit message that Morocco could repeat or escalate such pressure at will. Ceuta as a Sovereignty Flashpoint The Ceuta crises illuminate several dimensions of the relationship between migration instrumentalisation and sovereignty. First, Morocco does not recognise Spanish sovereignty over Ceuta and Melilla, considering them territories pending decolonisation. Each migratory avalanche therefore constitutes a direct challenge to Spanish sovereignty. The instrumentalisation of migration is embedded in a broader irredentist narrative. Second, the geographical asymmetry between Spain and Morocco creates a structural vulnerability. Spain’s North African enclaves are physically contiguous with Moroccan territory, making them uniquely susceptible to land based migratory pressure. This geographical reality gives Morocco a permanent source of leverage that it can activate whenever diplomatic relations deteriorate. Third, the legal constraints on Spanish responses further complicate the sovereignty challenge. The 2026 crisis was exacerbated by a Supreme Court ruling that migrants stopped at sea cannot be summarily returned to Morocco. This judicial constraint on executive action illustrates how domestic legal frameworks, even those grounded in human rights principles, can become vectors through which instrumentalisation achieves its destabilising effects. The instrumentalising state can exploit legal vulnerabilities in the target’s migration regime. The 2015 European Migration Crisis and the Sovereignty Question The Crisis and Its Scale The 2015 European migration crisis marked a watershed moment in the relationship between migration and sovereignty in the European context. More than one million refugees and other migrants entered the European Union during that year, with the influx straining the bloc’s asylum systems, exposing divisions among member states, and fundamentally challenging the premises of the Schengen area. The crisis originated primarily from Syria’s civil war, but its consequences were mediated through the institutional architecture of European integration. The crisis exposed what has been described as a normative dissensus among EU member states regarding migration governance. Countries at the end of the Balkan route, including Germany, Hungary, and Austria, adopted divergent approaches that reflected contrasting conceptions of sovereignty, solidarity, and humanitarian obligation. The crisis revealed the strength of the idea of national sovereignty within member states, indicating that supranationalism remains nascent and intergovernmentalism readily transforms into a self help mechanism to opt out from common European destiny in times of crisis. The Schengen Area Under Pressure The Schengen area, which had abolished internal border controls among 26 countries, came under unprecedented strain. The crisis forced a fundamental reckoning with the tension between open internal borders and the effective control of external frontiers. Several member states reintroduced internal border controls, invoking emergency provisions in the Schengen Borders Code that permit temporary restrictions in response to extraordinary surges of migrants. The European Commission proposed the creation of a standing European Border and Coast Guard with the extraordinary power to dispatch border guards to porous frontiers even if the member state concerned did not want the help. This proposal directly challenged a cardinal principle of sovereignty: a country’s responsibility for its own borders. The debate over the proposal revealed deep divisions between countries like Germany and France, which favoured stronger common border controls, and nationalist governments in Poland and Hungary, which opposed ceding any powers to Brussels. The crisis also prompted the EU Turkey migration deal of March 2016, under which Turkey received financial assistance and political concessions in return for clamping down on its borders and keeping refugees in the country. This arrangement externalised border control to a non member state, raising questions about whether sovereignty over borders can legitimately be delegated to third countries. The deal illustrated how migration governance increasingly involves complex arrangements that blur the lines between state sovereignty and international cooperation. National Responses and Sovereignty Assertions Individual member states responded to the 2015 crisis in ways that asserted national sovereignty against EU level solutions. Hungary constructed a 175 kilometre fence along its border with Serbia, a decision that Serbian Prime Minister Aleksandar Vucic described as surprising and shocking. The UN refugee agency condemned the fence, expressing concern that it placed too many barriers on the right to seek asylum. Hungary justified the fence as a necessary response to EU inaction, with its foreign minister stating that with EU efforts towards a satisfactory joint approach proving to be long and time consuming, Hungary could not afford to wait any longer. Germany, by contrast, initially responded with openness, with Chancellor Angela Merkel deciding that Germany would no longer adhere to the Dublin rules requiring refugees to be returned to the country of first entry. This decision, however, accelerated flows toward Germany and ultimately prompted the reintroduction of border controls with other Schengen states. The German case illustrates how even humanitarian responses to migration can generate sovereignty challenges, as the perception of lost border control undermined public confidence in the state’s capacity to manage its frontiers. The 2015 crisis thus generated a paradox: the very mechanisms designed to pool sovereignty and create common European governance, such as Schengen and the Common European Asylum System, became sites of sovereignty contestation. Member states reasserted national control over borders while simultaneously demanding that the EU strengthen its external frontier. The crisis revealed that sovereignty in the migration context is a relational concept, constantly negotiated between national and supranational levels. Broader Patterns of Migration Instrumentalisation The Belarus Poland Border Crisis The Belarus Poland border crisis, which began in 2021 and continued through 2024, represents a different modality of instrumentalisation: systematic hybrid warfare conducted by a state against the European Union. Belarus, in coordination with Russia, orchestrated migrant flows through the issuance of visas, the arrangement of flights, and logistical facilitation, embedding these operations in a broader disinformation and pressure campaign. From July 2021 to November 2024, the Polish Border Guard recorded 110,595 attempts to cross the Polish Belarusian border illegally. Belarusian authorities granted thousands of migrants from the Middle East visas to visit Belarus and then escorted them to the borders of Poland, Lithuania, and Latvia. The migrants were effectively used as pawns in a geopolitical confrontation, with Belarus retaliating against EU sanctions imposed following its crackdown on political opposition. The European Parliament explicitly recognised that hybrid threats arising from the weaponisation of migration by Russia, assisted by Belarus, pose a risk to the sovereignty, national security, and territorial integrity of concerned member states. The crisis forced Poland to deploy military forces to its border and to consider suspending the right to asylum for certain categories of migrants. The Belarus case reveals how instrumentalisation can operate through systematic state orchestration rather than mere relaxation of border controls. Belarus did not simply allow migrants to approach its border; it actively recruited, transported, and directed them toward EU frontiers. This represents a qualitatively different level of instrumentalisation, one that approaches the threshold of armed aggression through non military means. Turkey’s Migration Leverage Turkey has similarly employed migration as a source of geopolitical leverage against the European Union. In early 2020, Turkey unilaterally opened its borders with Greece, allowing migrants and refugees to enter the EU. This action was part of an attempt to garner more financial and military support from the EU, using migratory flows as leverage. Turkey’s tactics in handling refugees as a means of negotiation leverage not only explain but also prove that country’s strategic advances to elicit power and prevail as a major regional power. The 2016 EU Turkey migration deal itself was a product of this leverage dynamic. Turkey received 3 billion euros and political concessions, including the prospect of visa free travel for Turkish citizens in the Schengen area, in exchange for clamping down on its borders. The deal institutionalised a relationship in which migration control became a bargaining chip in broader geopolitical negotiations. The Turkish case demonstrates that instrumentalisation is not limited to authoritarian regimes but can be employed by states with complex relationships with the EU. Turkey’s status as a NATO member and candidate for EU membership has not prevented it from using migration as a tool of coercion. The instrumentalisation of migration has become a recognised instrument of statecraft in the Eastern Mediterranean, with Greece and the EU repeatedly forced to respond to Turkish generated migratory pressure. The Western Sahara Dimension The Morocco Spain cases are situated within the broader Western Sahara dispute, which has generated recurring migration instrumentalisation. Morocco seeks international support for its plan to establish Western Sahara as an autonomous region under Moroccan sovereignty. The kingdom has consistently used migration cooperation as a diplomatic tool to obtain recognition of its claims. The 2021 Ceuta crisis achieved Morocco’s objective of securing Spain’s explicit recognition of Moroccan sovereignty over Western Sahara. This success established a precedent that other states have observed and potentially emulated. The 2026 crisis, occurring after Spain had already recognised Moroccan sovereignty, suggests that instrumentalisation can be reactivated whenever Morocco perceives its interests are threatened, regardless of prior concessions. The Western Sahara dimension illustrates how migration instrumentalisation is often embedded in longer term territorial disputes. The instrumentalising state does not merely seek immediate concessions but uses migration pressure to advance fundamental claims about sovereignty and territorial integrity. The target state’s vulnerability to migratory pressure becomes a permanent feature of the bilateral relationship, constraining its diplomatic options. Legal and Institutional Responses The EU Legal Framework The European Union has developed a legal framework specifically addressing the instrumentalisation of migration. The Crisis and Force Majeure Regulation provides for procedural derogations from common asylum rules that member states may be authorised to apply in situations of crisis, including instrumentalisation. The revised Schengen Borders Code allows member states to temporarily close border crossing points in cases of instrumentalisation while guaranteeing access to international protection procedures. The EU Asylum Agency, the European Border and Coast Guard Agency, and Europol can provide support to member states facing situations of instrumentalisation. The European Commission has issued communications on countering hybrid threats from the weaponisation of migration, recognising the phenomenon as a security challenge requiring coordinated response. However, the legal framework faces significant limitations. The distinction between instrumentalisation and ordinary irregular migration is difficult to operationalise. Member states may be tempted to invoke instrumentalisation as a justification for restrictive measures that would otherwise violate fundamental rights. The European Union Agency for Fundamental Rights has warned that measures to counter instrumentalisation must be implemented in full compliance with fundamental rights. The Sovereignty Dilemma The legal and institutional responses to instrumentalisation embody a fundamental sovereignty dilemma. Effective countermeasures require cooperation among states, which implies some pooling of sovereignty. Yet the very states most vulnerable to instrumentalisation are often reluctant to cede border control authority to supranational bodies. Spain, for example, rejected Frontex assistance during the 2021 Ceuta crisis, preferring to manage the situation bilaterally with Morocco. This reluctance reflects the reality that border control remains a core attribute of sovereignty that states are unwilling to delegate. The paradox is that the defence of sovereignty against instrumentalisation may require the very kind of international cooperation that sovereignty purists resist. States want the benefits of collective border security without the corresponding loss of national control. The Limits of Law International law provides limited remedies against instrumentalisation. The instrumentalising state does not typically violate explicit treaty obligations by relaxing its own border controls, as states retain the sovereign right to determine who enters their territory. The migrants themselves may not be acting unlawfully in seeking asylum, and their treatment is governed by refugee law and human rights standards. The concept of instrumentalisation is therefore largely a political and policy construct rather than a well defined legal category. This limits the effectiveness of legal responses and leaves states reliant on diplomatic pressure, economic sanctions, or military deterrence. The weaponisation of migration exploits a gap in the international legal order: states have duties to protect refugees but limited obligations to prevent their departure. The instrumentalisation of migration represents a fundamental challenge to state sovereignty in the contemporary international system. The cases examined in this study reveal a consistent pattern: states with geographical leverage over migratory routes can generate sudden surges of irregular migration to pressure target states, extract concessions, or destabilise political systems. The Ceuta crises of 2021 and 2026 demonstrate how Morocco has used migration as a tool of coercive diplomacy against Spain, achieving its objective of securing recognition of its claims over Western Sahara. The 2015 European migration crisis exposed the fragility of the Schengen area and the tensions between national sovereignty and supranational governance. The Belarus Poland border crisis and Turkey’s migration leverage illustrate the broader geopolitical dimensions of instrumentalisation. The sovereignty implications of these phenomena are profound. When a state loses the capacity to control its borders, its sovereign authority is materially diminished. Yet the defence of sovereignty against instrumentalisation requires cooperation that itself entails some surrender of sovereign prerogatives. This paradox lies at the heart of contemporary migration governance. The international community has been slow to develop effective responses to instrumentalisation. Legal frameworks remain incomplete, institutional capacities are uneven, and political will is often lacking. The weaponisation of migration has become an established tool of statecraft, and its use is likely to increase as geopolitical competition intensifies. States vulnerable to migratory pressure must develop both defensive capabilities and diplomatic strategies to counter this threat, while respecting their obligations to protect the human rights of migrants. The cases of Ceuta, the 2015 crisis, Belarus, and Turkey are manifestations of a broader transformation in the relationship between migration and sovereignty. In an era of interconnectedness, borders sites of contestation where state power is tested and often found wanting. The instrumentalisation of migration exploits this vulnerability, turning human mobility into a weapon against the very concept of sovereign statehood.