True, India is an ally of Russia and not USA/West. But in case of war, USA can do three things:
1. Support China: China has similar military to USA and 4x the population. If USA does support them, china will strongarm literally every country in the world and become the hegemon.
2. Stay Neutral: This would mean every bigger country can attack and capture nearby smaller ones. The reason expansion wars don't happen now is because of the fear of US.
3. Support India: If US is to counter China, this means supporting India.