Made permanent enemies of Pakistan after 1971? Can you tell which times before that Pakistan was friend? Also there were millions of people from Bangladesh running to India before 1971 supporting which had become a major problem and beyond resources of India. BTW, this forced migration was one of the reasons of the war. Please study some more on this war and you will know. Had Bangladesh not been created, there would have been much more problems like terrorism on both sides of India, huge immigration attempts from Bangladesh etc..
