What about Russia nowadays the problem is that there many immigrants from adjacent under-developed countries. Really a great deal of them, especially in Moscow. They have another culture that seems to us barbaric, as maybe many of Russian people seems barbaric for Europeans. They don't know our language. Savagery, bad manners, some kind of dissoluteness and even crime and so on. That's a problem! A problem occurs when two cultures differ very much, and both strive for dominance.
In Moscow an invasion of lower-paid unskilled workers is lasting for at least ten years. Here is an example, if you, a common Moscow family, decide to meet a New Year in the heart of Russia, on the Square near Kremlin, and you go there to see a salute, you'll be afraid of what you see and you'll run away in a hurry - thousands of slovenly and dirty, smoking, drinking, scolding foreign people all around, who even don't know Russian language. In ordinary days large groups of such people you can meet here and there in Moscow streets. I've read that resembling state of affairs is in many parts of Europe too (Brussels, Paris, Italy towns)...
P.S. Forget to mention, 90% of these newcomers are Mussulmen.