There is no such thing as "moral" in international diplomacy. The ultimate concern of a nation-state is self-preservation that guides its behavior in its relationship with other nation-states. It is rightly said that there are no permanent friends or permanent foes in international relations; there are only permanent interests. Presently, India's interest lies in energy security. The nuclear-weapons capability acquired by it so far is encouraging. US agreed to break ranks and sign such an unprecedented nuclear deal with India not because of any enlightened concern for the energy requirements of India, but because it thinks that wider engagement with an emerging India would help further its self-interest in international affairs. If at any point in time the needs of the country are served better by more nuclear tests then that will be the course of action. Like with any other country, nuclear testing will have its own consequences in the short-term. But if the benefits outweigh the costs (which it will, given the global importance)then no "moral" obligation will stop it from doing it; there was none to begin with.
