Functional Adaptation Without Much Love: NATO and the Strains of EU–US Relations

This chapter examines how Donald Trump’s return to the White House in 2025 has transformed the EU–NATO–US triangle and Europe’s security architecture. Trump’s open questioning of Article 5, his transactional approach to allies, the US pivot to the Indo–Pacific, and renewed scepticism toward multilateral institutions have triggered a crisis of confidence in Washington’s security guarantees. In response, European states have increased defence spending; the EU has assumed a more assertive role in defence industrial and fiscal policy; and flexible coalitions, such as the ‘coalition of the willing’ for Ukraine, have proliferated. Taken together, these developments point not to transatlantic breakdown or full renewal, but to a ‘muddling through’ scenario of adaptive equilibrium, in which mutual dependence, institutional resilience and emerging European capabilities sustain the partnership despite deep mistrust. The chapter closes by outlining key policy priorities for managing this uneasy but durable settlement. Keywords: NATO; European Union; security; defence; multilateralism; populism