Replacing the US nuclear guarantee with a French nuclear umbrella for Europe would face major political and logistical challenges. Nevertheless, given the growing un­certainty in Europe and Asia, the German government should consider scenarios and options that go beyond today’s deterrence...

While a second Trump Presidency would be challenging for transatlantic ties, US nuclear assurances to its NATO allies in Europe would likely be the last casualty - not the first - of a fraying relationship. There is an intrinsic incompatibility between the United States completely abandoning its...