Salad bowl or melting pot — how you assimilate immigrants into your community has a good bit to do with homegrown terrorism. The American model is more prone to be a melting pot where all the cultures in the nation assimilate into a common culture. The taco becomes as much a national food as the hamburger and hot dog. Increasingly, in the United States, the left wishes to employ a salad bowl approach, instead of a melting pot. The idea is that each culture lives together, but keeps strong distinctions between itself and the other. The lettuce may pick up the taste of the carrot while both are smothered in a common dressing, but they remain distinct.
European multiculturalism reflects the salad bowl model and it is going to keep getting them killed.
Throughout Europe, muslim immigrant communities stay in their ghettos, keeping their culture separate, while taking on the citizenship of their new countries. There are sections of Paris where you dare not go if you are Jewish. The same is true in parts of Sweden, Belgium, and even Great Britain now. Cultural fiefdoms outside the common cultural heritage of a nation have sprung up and as muslim populations begin exceeding 10%, problems start happening.
Chief among them, as Islam in these countries remains very distinct, it does not shed its economic and political tenets while holding onto its religious tenets. They are interwoven in such a way that they are already hard to separate. In European societies that increasingly apologize for their own heritages while bending over backwards to accommodate the heritage of new immigrants, the work is even harder.
This is another good reason for Britain to get out of the EU. The European Union has embraced salad bowl multiculturalism at large. The EU already has problems building a common European culture among diverse nation-states with long histories. It is positively incapable of dealing with the addition of Middle Eastern immigrants.
The further away from the melting pot idea of assimilation this nation gets, the worse it will get here. We can look to Europe and see. If would be a good thing if the British move out of the EU and move back to requiring its immigrants to embrace British values.