In the years after Nato was formed in 1949, its US and European members had a collective approach to defence with clear goals in common, largely built around the protection of western Europe against the Soviet Union. Throughout this era, the US and Europe both relied on the stability of the international system by creating international cooperation on shared dilemmas.
Fast forward more than 70 years, and there is now a ticking clock on reinventing the transatlantic alliance.
European security and US-led Nato security are no longer one and the same. Certainly, recent statements from US leaders that the US will prioritise empowering Europe to own responsibility for its own security has made for tough listening in Europe.
