Jack Detsch, gatewayhouse.in
[F]or New Delhi, Tehran can also be a multilateral troublemaker as Iran has used its seat on the Organisation of the Islamic Conference to condemn India’s conduct in Kashmir.[11, 12]
That may have been par for the course. New Delhi has voted against Tehran several times at the International Atomic Energy Agency (IAEA) and enforced sanctions on the Islamic Republic, even after those penalties bit into two Indian companies that traded missile materials to Iran in 2005. 
Iran’s cold shoulder, however, was a tough blow to India. The world’s largest democracy houses the world’s second biggest Shia population. According to the Pew Research Center, more Muslims will live in India by mid-century than anywhere else on earth. Ties with Muslim communities outside India will come to weigh heavily on the country’s domestic politics. 
Public diplomacy is not the only element of India and Iran’s relationship that has fallen by the wayside. Facing the brunt of sanctions, India cut oil purchases from Iran to just 6% of its imports in 2015. That’s down from nearly three times that amount a few years ago. 
But that trend may not hold. India does not have the luxury of choosing its friends and allies from an ocean away. Living in a neighborhood with failing democracies and endemic poverty, India must go to great lengths to preserve energy relationships and political alliances, even if those ties aren’t built to last. ...