Helmholtz Watson said:
Obviously you have little knowledge of what you are speaking of, it sounds a lot like that North Korea documentary. What was it? Oh right, 'oh there is no birds left, except for the places they are left, they will be eaten on Tuesday'
It's generally nonsensical. Nationalism is a world-wide problem, it's 'not' only apparent during Football matches http://www.economist.com/node/21560882 if that was the case, it wouldn't be a problem. Besides, Football Matches are more than nationalism, really it goes deeper than that and into a group mentality smaller than that of a country, football goers rarely 'really' think "Oh its England VS Spain" they think "It's Lancaster VS Barcelona" At least the proper fans. Clubs representing the countries are not always the best, nor the ones whom win.
You addressed that it was a problem other places, but that it was only valid because there'd been a World War in Europe. But that kind of disregards the fact that there was another Ultra-Nationalist country, youknow. Japan.
Of course the war between the Empire of Japan and China never amounted to anything big, only a few twentymillion dead, small stuff. Not to talk about the fact that this exact war has mostly created what we know as Chineese Nationalism, which might cause some big problems in the future.
South Korea is a bad example, mostly because they have at several times wanted to act like Israel going gung-hoh on a nearby nation almost universally hated, but just as with Iran there have been quite a few countries 'not' wanting to start a war. Youknow, because South Korea wouldn't be the only country going to war, every western nation would be forced into the conflict.
Golden Dawn in Greece is also a poor example, the massive wave of support came in large to lack of alternative, it is once again falling and is most probably gonna balance around the same as the rest of its kind.
"Nationalism has been closely associated with the most destructive wars of human history; the revisionist states responsible for initiating both the First and the Second World Wars have historically been examined as the epitome of the dangers of nationalism. However, it must be noted that whilst there is a great deal of academic literature surrounding nationalism as a social and political phenomenon, there is little concerning the causal link between nationalism and war, scholars often taking the ?war-causing character of nationalism for granted?[1]. A nationalist group can be defined as a set of individuals holding their most important loyalty to their ethnic or national group, with this superseding other loyalties (such as political ideology, religious ideology, etc)"
As we can see, the only place this would really be a problem would be America, luckily most of the people there are in too bad shape and too lazy to start shooting at some other nation, this is why most wars we see caused by Nationalism today is in Africa, Middle East or in some cases Asia. Only people in bad enough shape and lazy enough to do something about their hatred for other cultures.
It's quite simple. While Religion has without doubt contribtued to every single war on Earth, where Nationalism has not. What sets them apart is that Religion is the main reason for war very rarely, whereas Nationalism has been the reason for some of the most devastating war we have 'ever' faced. It's not something you want to make light of, and seeing the main spokespeople of nationalism (The Extreme Right, Ultra-Religious, Conservatives) It doesn't encourage much trust in the modern movements.
As a final word, and to rebute some of the things you were bound to say if you were to respond.
Globalism (NATO, UN, EU) are not just a contributing factor, but I'd say the MAIN reason that Nationalism will not get as much of a hold anywhere as it used to. The fact that as countries we have to communicate and trade, that alone. Is pretty much enough to strengthen bonds over time to prevent what is required by Nationalism to spark wars.