When an incursion of Russian drones forced Warsaw Airport to shut down recently, Poland immediately shot them down. When unidentified drones forced Munich Airport to suspend operations last September, German authorities provided snacks for stranded passengers while police helicopters monitored the air space. As strange as it may sound, Germany’s military isn’t allowed to defend German airspace against anything short of a full-scale invasion. It’s just one roadblock of many in the way of making Germany fighting fit.

On paper, Berlin has a free pass to strengthen national defense. With military spending above 1% gross domestic product exempted from borrowing restrictions, there is effectively no limit on funding of the military, known as the Bundeswehr. But as the drone dilemma indicates, Germany faces more daunting obstacles to defending itself as the neighborhood gets increasingly dangerous.

For one, the Constitution, written after World War II, strictly limits the military’s role inside the country, even banning it from shooting down flying objects such as drones anywhere in domestic airspace that isn’t above a military base. This rule was meant to prevent the kind of military overreach seen during authoritarian times, especially under the Nazi regime. Today, these restrictions make it hard to respond to modern threats.