Bases of Contention: Spain, the United States, and the European Fragmentation of the Transatlantic Alliance

The war in the Middle East has brought about serious changes to the U.S.-Spanish defense relationship. Spain’s restrictions to the U.S. use of military bases and access to the airspace for U.S. aircraft for all operations against Iran have sparked intense debates around the future of Spanish and European defense’s allyship with the U.S. The U.S.-Spain defense partnership which spans seven decades is deteriorating alongside NATO, calling into question the reliability of future collaborations. Spain’s response to the war on Iran is more than a temporary breakdown. It is evidence of a broader shift towards a reduced reliance on U.S. defense support. 

The Fragmentation of U.S.-Spain Relations

The War on Iran began after U.S.-Israel strikes against nuclear targets sparked a regional war, which began in late February 2026 and has no real end in sight, and which has had serious global consequences. The international community’s response is lacking in the ability to find a solution that will curb the economic disruption the conflict has ignited. Spain’s response to restrict access to military bases, as well as access to the country’s airspace for the use of operations against Iran, reflects its attitude towards the legality of this war. These restrictions have resulted in disruption to some of the U.S.’s operations that required access to its bases in Spain. 

Refueling missions were redirected after the restrictions were implemented, requiring the U.S. to collaborate with France and Germany instead. This meant the deployment of 15 refueling aircraft had to be rerouted to other U.S. bases in Europe. Rerouting meant longer and less efficient routes, demonstrating how Spanish policy can constrain the U.S.’s actions. This interference led to retaliatory actions toward Spain from the Trump administration which threatened to halt all trade between the two. Retaliatory measures had previously been taken in response to the growing tension between the U.S. and Spain over financial contributions to NATO. Trump’s push for Spain’s removal from the Alliance in 2025 came as Sanchez’s government refused to commit 5% of its budget to security spending. 

A Revaluation of the ´Pact of Madrid´ 

Spain has consistently held a pivotal strategic position in the United States’ defense in Europe, North Africa, and the Middle East. The Trump administration may come to encounter yet greater challenges in future missions, considering the indispensable role of Spain as an access point to the Mediterranean, greater Europe, and Africa. The jointly run bases, which Spain has denied access to, have played a pivotal role in the U.S.’s operations since the early 1950s. The Pact of Madrid (1953) established the five U.S. bases on Spanish territory, in exchange for economic and military aid. This pact remains an active agreement between the U.S. and Spain, despite the current tensions. Two key bases have played critical roles in U.S. operations for over seven decades. The naval base in Rota, which has been key for U.S. naval operations in the Mediterranean, and the base in Morón, an airbase used for the deployment of brigades rapidly in the Mediterranean and Africa. By restricting U.S. access to these bases for actions in Iran, Spain’s stance is further evidence of the decoupling taking place between the two over the last three years. 

During the Israel-Hamas War, Spanish Prime Minister Pedro Sanchez was at the forefront of European leaders speaking out about the disproportionate response to the October 7th attacks, citing humanitarian concerns and the consequences the conflict had on regional stability. Following this condemnation, U.S.-Israel actions during the 12-day war of June 2025 led Spain to further condemn the illegal aspects of U.S.-Israel aggression, given the lack of U.N. authorization. By February 28th of this year, U.S.-Israeli actions pushed PM Sanchez and his cabinet to begin taking greater action against further escalation, resulting in the restricted use of Spanish military assets. Beyond restricting access to military assets, Sanchez has taken further action against the U.S.-Israel aggression, removing the Spanish ambassador to Israel. The closure of the Strait of Hormuz and the NATO members’ reluctance to assist the U.S. in reopening it have called into question the defense relationship between the U.S. and its NATO allies. 

The Future of European Defense: Strategic Autonomy or a Return to Status-Quo 

What comes next falls into three possible categories: a restoration of past relations, a move towards strategic autonomy in EU defense capabilities, or a more selective form of collaboration between the U.S. and its European allies. The first of these three possibilities, a return to the status quo, would see continued defense cooperation and commitment to the NATO alliance. This seems unlikely given the gap in capabilities the EU members will suffer without U.S. support. Moreover, the attitude President Trump has displayed towards supporting an alliance that the U.S. funds but does not have unilateral control over seems to be the largest indicator of the irreparability of this partnership. For Spain, this outcome is attached to the risk of weakened defense capabilities, given the long-standing history of bilateral and multilateral defense arrangements with the U.S. Reflecting on the past condemnation of U.S. action in Iraq from Spain in 2003, there is a possibility that the alliance will not be permanently ruptured. 

The second potential outcome, where Europe abandons U.S. defense support entirely, seems a likely consequence of the increased pressure on European leaders to search for greater autonomy and even independence. This outcome is often met with a lack of ability to find EU-wide consensus on a unified defense program and insufficient attempts to deepen European integration on defense. While EU leaders have prioritized defense autonomy in light of the realities of the war on the continent’s eastern front, it remains a goal rather than a tangible reality. As many EU states remain heavily reliant on U.S. defense funding and material support, including Spain, this outcome presents serious barriers to implementation.

The most realistic of the three outcomes is a combination of the previous two, a shift towards a more selective cooperation with the U.S. This possibility would result in optional support of U.S. operations, avoiding those that qualify as offensive. Furthermore, it is essential to this outcome that Spain and its European partners emphasize legal military actions and offer support on a case-by-case basis to prevent further aggression. Maintaining diplomatic relations with the U.S. is crucial for Spanish and EU security, as U.S. support has played a crucial role in defense against the Russian aggression in Ukraine. This mutually beneficial outcome would ensure the continued existence of NATO and enable a more stable transition towards a more independent European defense community. 

Conclusion

The Iran conflict has revealed a structural change in the defense relationship between the U.S. and Spain. The denial of support for U.S. operations has demonstrated that the alliance, once conditional, seems to become subject to constraints in light of the political motives and legality behind the offensive action against Iran. This shift comes against the background of broader tensions emerging between the U.S. and its European allies in NATO, with the discontent is apparent on both sides. A complete breakdown of the relationship seems improbable, but so does a return to the pre-conflict status of unity. The turn towards a model which focuses on selective cooperation is defining the future of U.S.-Spanish and broader U.S.-European relations. Spain’s response to the Iran conflict may not be unique. Rather, it is a clear indicator of greater fragmentation within the trans-atlantic relations and the NATO alliance system.

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Macy Ellis graduated from Saint Louis University–Madrid with a degree in Political Science and minors in Philosophy and International Studies. Having lived and studied in both Spain and the Czech Republic, she has developed a strong interest in comparative legal systems, international governance, and the ways legal institutions operate across different political contexts. Her research interests include international law, development aid, and international cooperation.

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To quote this article, please use the following reference:

Ellis, Macy. “Bases of Contention: Spain, the United States, and the European Fragmentation of the Transatlantic Alliance.” Observatory On Contemporary Crises, Observatory On Contemporary Crises, June 2026, www.crisesobservatory.org/post/bases-of-contention-spain-the-united-states-and-the-european-fragmentation-of-the-transatlantic-a.