China, a key member, has always obstructed India's entry into the 48-member Nuclear Suppliers Group. Beijing has argued that Delhi was not part of the Nuclear Non-Proliferation Treaty. On the other hand, China has been supporting Pakistan's, which had applied for NSG membership in 2016, entry to the group.
Barring the NSG, India has gained entry in the remaining three important export control regimes--- Missile Technology Control Regime, Wassenaar Agreement and the Australia Group.