International alliances are arrangements between state parties that bind them to cooperate militarily, diplomatically or economically in support of a shared cause. These causes can be national security, development or a range of other political and economic goals. They often entail a degree of sacrifice of sovereignty and so are inherently a source of tension and risk for member states.
Alliances are never automatic or guaranteed despite being based on the strictest treaties and political commitments. Whether it is the United States’ invocation of Article 5 after 9/11 to defend its allies against terrorist attacks or a European Union response to Russia’s intervention in Ukraine, full discharge of an ally’s obligations requires consultation and collective action that can be disrupted by domestic politics in allied capitals or their allocation of resources.
Moreover, the success of an alliance depends on its ability to adapt to change in the strategic context that created it. NATO’s alliance with Russia and the EU’s formation in Europe are examples of how these organizations evolved into more than just a common foe, as the end of the Cold War allowed them to take on new missions that expanded their reach.
Nonetheless, the utilitarian value of alliances is often overshadowed by the more nebulous sense that they are expressions of a shared moral purpose or an unalloyed good. The reality is that they are a critical tool for countries engaging in great power competition, but they must be viewed with a higher level of realism.
