The controversies the North Atlantic Treaty Organization (NATO) has faced in recent times are a sign not only of military but also of political and institutional tensions. In particular, the differences in perspective that have emerged between the United States (U.S.) and its European allies in the context of the Iran War raise significant questions about the alliance’s resilience and operational mechanisms. In this context, the debate over “suspension of membership” sparked by Spain’s stance clearly highlights the discrepancy between NATO’s legal framework and political reality.
First and foremost, the statement made by NATO officials is extremely clear when evaluated within the framework of the North Atlantic Treaty, the alliance’s founding document: There is no provision within the alliance for the suspension or expulsion of a member. This situation demonstrates that NATO, by its very nature, is a structure based on the principle of “voluntary membership.” Consequently, indirect methods such as political pressure, diplomatic isolation, or changes in the distribution of duties take precedence over sanctions like expulsion from membership.
However, a document reportedly drafted within the Pentagon in the U.S. indicates that tougher measures against allies are being discussed. In particular, Spain’s refusal to support the U.S. in military operations against Iran is viewed by Washington as “insufficient solidarity.”[i] The Spanish government’s refusal to allow bases on its territory to be used against Iran serves as a concrete example of this tension. Spanish Prime Minister Pedro Sánchez, however, has rejected these claims, emphasizing that his country is acting in accordance with international law.[ii]
At this point, a significant structural issue regarding NATO’s functioning comes to light. Although the Alliance is based on the principle of collective defense, member states’ foreign policy priorities and perceptions of threats do not always align. In particular, the fact that European countries adopt a more cautious approach on a contentious issue such as Iran conflicts with U.S. expectations. This situation once again demonstrates that NATO is not merely a military alliance but also a mechanism for political consensus.
U.S. President Donald Trump’s criticisms of NATO also form a significant part of this debate. Trump’s characterization of the alliance as a “one-way street” and his accusation that European countries are “free-riders” have brought long-standing tensions in transatlantic relations back into the spotlight.[iii] These criticisms are being expressed in harsher terms, particularly in the context of the crisis with Iran.
Iran’s tightening of its control over the Strait of Hormuz and the disruption of global energy trade are further deepening divisions within NATO. While the U.S. views this situation as a direct security threat, European countries are leaning more toward seeking a diplomatic solution. This divergence is making it difficult for the alliance to develop a common strategy.
The United Kingdom’s stance serves as a middle ground in this divide. The UK provides some support for U.S. operations against Iran; however, it maintains a cautious approach to prevent the conflict from escalating. Prime Minister Keir Starmer has stated that further military engagement is not in the country’s interest.[iv] This situation indicates that the “limited support” approach is becoming increasingly widespread within NATO.
Another notable element in the document prepared by the Pentagon is the implication that the U.S. might reassess certain “historical issues” in Europe. In particular, the raising of the sovereignty dispute over the Falkland Islands is seen as a new leverage tool in transatlantic relations. Such steps demonstrate that NATO has evolved into a broad political bargaining arena beyond its role as a military alliance.
Italian Prime Minister Giorgia Meloni’s emphasis on NATO as a “source of strength” and her call to strengthen the European pillar serve as a response to these discussions. Similarly, Germany’s assertion that Spain’s membership is non-negotiable indicates that European countries are striving to preserve the message of unity within the alliance.[v]
Despite all these explanations, it is evident that tensions within NATO have taken on a structural nature. In particular, the United States’ demand for greater military and political contributions from its allies has become a decisive factor for the alliance’s future. This situation brings the question of how NATO’s principle of “collective defense” is applied in practice back to the forefront.
These developments clearly demonstrate that NATO is not merely a military alliance but a complex political structure comprising states with differing threat perceptions and foreign policy priorities. In particular, the contrast between Spain’s more cautious stance, emphasizing international law, and the United States’ more interventionist approach is deepening strategic misalignment within the alliance. Although NATO’s institutional structure possesses the flexibility to accommodate members’ divergent interests, such crises reveal the limits of the alliance’s capacity for collective action. Consequently, the division emerging in the context of the Iran War is prompting questions not only about the alliance’s future operational effectiveness but also about its political cohesion.
Ultimately, the debate sparked by Spain highlights NATO’s political dynamics rather than its legal structure. Members’ positions within the alliance are determined not only by formal rules but also by power balances, strategic interests, and diplomatic relations. In this context, NATO’s future will be shaped by how such tensions among members are managed. In this regard, to ensure the alliance’s sustainability, it is necessary to strengthen not only military capabilities but also political cohesion. Otherwise, the possibility that even an established institution like NATO could lose its effectiveness due to internal divisions is becoming an increasingly debated issue.
[i] Walker, Amy, “Nato says ‘no provision’ to expel members after report US could seek to suspend Spain.”, BBC News, https://www.bbc.com/news/articles/cz78x703lrvo, (Date of Access: 26.04.2026).
[ii] Ibid.
[iii] Ibid.
[iv] Ibid.
[v] Ibid.
