If your arguments are true they can do it even now and even withou the TREATY! These arguments similar arguments were used for foreign investment in India. But without such economic benefits, India can't solve infrastructure problems and at the same time US can't afford to ignore India's importance worldwide. If every other country thinks India is not "CLEAN" then India will be in trouble like Pakistan. If only US thinks so, it won't make much difference because India can buy supplies from other states. They put economic sanctions on us but it didn't make much difference. In the same period, economic liberalisation allowed FDI into India. More importantly India too have its own resources to handle such pressures with or without treaty. The whole point is about technological and economic benefits and not about nuclear tests
