Pax Europaea ( – after the historical Pax Romana), was the period of relative peace experienced by Europe following World War II, in which there were notably few international conflicts or wars between European states. This peace had often been associated with the creation of NATO, the European Union (EU), and the predecessor institutions of the EU including the European Economic Community. This era of relative peace was broadly maintained following the end of the Cold War and the Dissolution of the Soviet Union, with the major exceptions of the Yugoslav Wars, The Troubles in Northern Ireland, and various tensions and wars involving or within Russia. Following the 2022 Russian Invasion of Ukraine, this period was seen to have ended, with the conflict inducing the largest war on European soil since World War II, and the largest European refugee crisis since World War II. History Transatlantic cooperation and European integration was designed to maintain the fragile peace that was created in Europe after World War II. 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. Although Central and Eastern Europe remained under Soviet influence as members of the Warsaw Pact, they too experienced little conflict, with the major exception of internal repression, until the 1990s when a series of wars in Yugoslavia broke out as the country disintegrated. The EU was criticised for its inability to prevent the conflict, though the zone is now within its sphere of enlargement. By 2020, the EU comprised 27 countries, with the majority of European non-member states seeking membership; twelve countries joined the EU in 2000s. In addition, most European countries which remain outside the EU are tied to it by economic agreements and treaties such as the European Economic Area. Although a number of former Soviet republics have joined the EU, or have taken steps to align themselves with various European organisations, Russia has maintained a level of independence from European institutions. Within