@IDL
Thats a bad premise because the world at large is under the period of Pax Americana and the threat of nuclear war.
You can rest assured that if America retreated back to isolationism and Monroe Doctrine and nukes were out of the picture, then war would certainly become an issue in the vast majority of Asia and Africa.
It is about European nationalism, and it is in contrast to globalism really.
You could argue that if the US empire retreated (thus creating a power vacuum) that this could lead to a new sort of large conflict on the world stage, in which case more power to a European government could become more useful. That is a factor, but it would apply to all nations really.
Also it is relative. What a rise in nationalism in modern day context in Europe represents is essentially a push back to the larger power consolidation represented by postnationalism and the undermining of the nations and sovereignty.
Thurisaz had this as a primary component to his argument.
I would agree though, that one of the benefits of empire in general is that it brings a stability on the macro level, and a certain degree of international government is desirable for this reason.
Too much power in that direction brings its own set of problems though, and also the devil is in the details.
It's a sort of tug-a-war between nationalism and globalism and a shift in one direction or another is a step in one direction or the other, not a complete slide in the binary sense. More of finding a balance.
So the premise I don't think is sturdy is that a shift towards nationalism within the context of Europe means a world war scenario or a major conflict of the sort. By the same reasoning, nationalism anywhere on the planet leads to this also. I don't think that is a good argument because nationalism does exist all over the place already, and in higher levels then what is currently in Europe (especially considering Europe is more post-national than most if not all places)