What were the reasons for the decline of nationalism in Europe after 1945?

Question

What were the reasons for the decline of nationalism in Europe after 1945?

Answer 1

Growth of the Cold-War system meant no nation could assert its will or gaurd its interests alone, leading to emphasis on international institutions, such as the UN, or EEC (European Economic Community, founded 1957).  An expansion of world trade and mass communication also helped contribute to a decline in nationalism.

Answer 2

The cold war made it necessary to decide whether to be on NATO's side or part of the Soviet Union's pawns.

Answer 3

Although the years following Word War II were marked by an increased cooperation among many of the western countries of Europe, nationalism never declined enough for a true United States of Europe, a goal that a number of European politicians pushed towards.  France still remained highly nationalistic, Britain remained wary for a long while towards trade agreements with the European continent, and West Germany was ever trying to gain favor with the United States to increase its influence on the continent.