Why has nationalism revived in Europe?

In the last decade or two, nationalism has not only not faded away in Europe, it has revived forcefully, and is now probably stronger than at any time since 1945. So far it has led to war only in former Yugoslavia and Ukraine, but it could easily become a threat to the peace of Europe elsewhere, so it is important to try and understand the underlying reasons for nationalism’s revival. In the Second World War, the peoples of Europe demonstrated to the full their capacity to inflict mass murder on one another in the name of integral and exclusive nationhood. A major cause of that war had been nationalist reaction to the breakdown of international trading systems in the 1930s: nation-states had been defending their own industries by raising tariffs and other barriers. After 1945 US and European statesmen were determined to prevent a repeat of these disasters.They set about creating international institutions which would enable nations to share risk, to consult together to preserve peace, to tackle economic or political crises collectively and cooperatively rather than individually and competitively, and to provide some degree of global governance to underpin international commerce. In other words, they worked to create positive-sum games and to broaden once more the radius of trust up to the global level required by economic developments.It was intended that nationalism should fade away, to be replaced by international cooperation, especially in dealing with crises.