Well, at the risk of sounding like a zenophobe (which I'm not, since I was once fresh off the boat myself, as an infant) often foreign students develop mental health issues during the years they are here. Some of it, I believe, has to do with their cultural isolation, frequently self imposed, while some has to do with their perceptions of being treated differently (especially if their English skills are weak). Very often, culture shock--especially relating to our customs, mores, and folkways are strange, conflicting and appear hypocritical (or even are). Often, foreign students that I have been in contact with over the years, seem to develop quite a lot of resentment, real or imagined, to life in the USA. As it happens, both VT tragedies were perpetrated by Asian students--South Korea and the People's Republic of China. As we know, both countries are rather conservative nations on the whole. The most difficult foreign students that I personally have had limited experience with, have been with those from Arabic or Muslim cultures. To me, it must be a terrible cultural shock for a Muslim to live, work, or study in the US. I'm not an apologist for the Muslim world, but there seems to be little in common between the two cultures.