With the continent repeatedly falling into war over the past centuries the creation of the European Communities in the 1950s set to integrate its members to such an extent that war between them would be impossible. Meanwhile, the North Atlantic Treaty Organisation formed as defensive military alliance among western European countries with the U.S. and Canada, to deter aggression both within and from without. The European Communities evolved into the European Union, and both it and NATO expanded to cover most of Western Europe, Northern Europe and Southern Europe.