回复：NIW申请，想要其他国家的推荐信，大家觉得用处大吗

I used one form my previous advisor of a school which is not in USA. Many friends of mine also used recommendation letters from scholors who are not Americans. In doing so they can prove your previous performance, which may be in consistence with your current performance. However, too many would not help. You may seek mostly from US scientists, but just one or two from the scientists of other countries, who had really close relationship with you, such as your advisor, previous boss. I think you should eliminate those ones who has no direct relationship with you.
Good luck!