The EU's Castor moment: from transatlantic unmooring to European self-definition

For much of the post-war era, the transatlantic relationship operated with a Castor-and-Pollux logic – twin allies whose strength derived from marching in lockstep. Today, that symmetry is gone. Washington’s strategic mood is shifting – its politics are volatile, its definition of democracy contested. The result is not a rupture but a transatlantic unmooring: a loosening of assumptions, certainties and dependencies that once felt immutable.
 
But the more the EU fixates on what has changed in the United States, the more it misses the deeper point: the test is not America’s transformation, but Europe’s own. External turbulence does not create European weakness – it merely exposes it.
 
A continent that disagrees on institutional reform, hesitates on defence and enlargement, and procrastinates on addressing the economic, technological and demographic revolutions ahead cannot blame the weather for being wet. Geopolitics is not mood management; it is preparation.
 
The lesson of the Dioscuri is not that the twins part ways, but that Castor must eventually find his own balance. This is Europe’s Castor moment – not an invitation to mirror American power, but to clarify its own strategic centre of gravity. The task is fundamentally inward-facing.
 
That means building cohesion where fragmentation persists, defining its democratic identity with greater confidence and advancing reforms that match the tempo of global change. The durability of the transatlantic partnership will depend not only on political developments in Washington, but on Europe’s capacity to articulate a coherent vision of its own role in a world that no longer guarantees external anchors.

Corina Stratulat is Associate Director and Head of the European Politics and Institutions Programme.

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