A long list of European states are contributing personnel and equipment to secure a pair of EU summits this week in Denmark. A spate of mystery drones in the buildup has exposed NATO's vulnerability to harassment and hybrid warfare.

We ask about unexplained flyovers, ghost ships and Russian denials. We also about spiking tensions across the Baltic Sea, where the stakes have never been higher since Moscow’s invasion of Ukraine.

From calls for "drone walls" to the return of conscription, how do Europeans beef up their own defence? And how much do they turn to NATO's historic guarantor, when the US seems to critics more interested in coveting Danish protectorate Greenland than defending against Russian expansion?

Produced by François Picard, Aline Bottin, Juliette Laffont, Ilayda Habip, Charles Wente.