On Friday, the United States and India will sign a very controversial agreement concerning India's nuclear program. The agreement "will provide India with access to U.S. nuclear fuel, reactors and technology, overturning a ban on such trade instituted after India first conducted a nuclear test in 1974." In exchange, India will agree to submit its nuclear facilities to oversight and inspections to ensure its security and stability.
The deal is controversial because India is not a signatory to the Nuclear Non-Proliferation Treaty (NPT) and its development and testing of a nuclear weapon is thus outside of the global non-proliferation regime, meaning that India is not supposed to be able to receive nuclear fuel and technology from NPT members. However, having a nuclear program as large and sophisticated as India's outside of any inspection or control regime was seen as problematic; thus the decision to make a deal that goes against the spirit and the law of the NPT.
The agreement constitutes, to some degree, a moral hazard. It sends a signal to other states that while the international community threatens to punish them if they proliferate, once nukes are a fait accompli, the international community will lift the sanctions in order to get the nuclear program under inspections. Thus, the disincentives for proliferation are moderated. The deal will, its critics argue, encourage more states to proliferate.
I don't buy this argument. The NPT has functioned better as a reward to states that do not want to proliferate than as a way of preventing the states that do want to proliferate from doing so. True, the NPT has made it more difficult for states to proliferate, but determined states (South Africa, India, Pakistan, Israel, North Korea, Iran) have managed to do so. These states have powerful security reasons to proliferate, and neither the threat of sanctions nor the incentives offered by the NPT are likely to overcome those reasons. So, the US deal with India is not likely to have any effect on the decisions of these states to proliferate.
Furthermore, other states aren't likely to develop nuclear weapons solely because India avoided punishment. Just look at the states of the Middle East that have, despite Israel's NW status, avoided proliferating. Their decisions not to proliferate are not based on fears of violating the NPT. Thus, the India deal is not likely to change their rationales either.
Ultimately, I don't see the deal as doing too much to undermine the global non-proliferation regime. States that want to proliferate will find ways to do so and the NPT does make it much more difficult for that to happen. But it is more important that India's nuclear program -- its fuel and materiel, its security systems -- come under international scrutiny than it is to make a point about the inviolate nature of the NPT.