On April 4, 1949, the North Atlantic Treaty was signed, enshrining the creation of NATO just four years after the end of World War II.

The primary objective of this military alliance of 12 European and North American countries was to prevent war in Europe and to counter the expansion of the Soviet bloc.

Since its creation in the Cold War, the organisation has grown from 12 to 31 member states - including several former Eastern Bloc nations.

Weakened by its turbulent history, NATO is facing a growing number of challenges: the difficulty of coordinating its members, the logistical obstacles in the event of an attack on European soil, and the threat, raised by Donald Trump, of an American withdrawal, at a time when European defence is almost entirely dependent on the United States.