English: The North Atlantic Alliance was founded in the aftermath of the Second World War. Its purpose was to secure peace in Europe, to promote cooperation among its members and to guard their freedom – all of this in the context of countering the threat posed at the time by the Soviet Union. The Alliance’s founding treaty was signed in Washington in 1949 by a dozen European and North American countries. It commits the Allies to democracy, individual liberty and the rule of law, as well as to peaceful resolution of disputes. Importantly, the treaty sets out the idea of collective defence, meaning that an attack against one Ally is considered as an attack against all Allies. The North Atlantic Treaty Organization – or NATO – ensures that the security of its European member countries is inseparably linked to that of its North American member countries. The Organization also provides a unique forum for dialogue and cooperation across the Atlantic. The Alliance started with 12 member countries in 1949. But membership has remained open to any European nation that shares transatlantic values and can contribute to security in the Euro-Atlantic area. Today, NATO has 28 members with Montenegro on the verge of joining. For over six decades, NATO has ensured peace within its territory. While threats, and the way NATO deals with them, have evolved over time, the purpose, values and founding principles of the Alliance do not change.