If India goes back on the deal following are the possible damages: 1. Future US admins would be reluctant to pursue any major deal with India 2. Any future Congress led govt will have credibility problem in world capitals 3. Even though the US might be weakened due to Iraq etc it is not a nation to be trifled with. Even China the next superpower doesn't openly humiliate the US or its president which India will end up doing by dumping the deal. 4. India would be only major economy that is boxed in the technology denial regime and would be handicapped in its quest for progress and prosperity 5. It would make it harder to come up with a commercial Thorium based FBR in the absence of research cooperation with other advanced nations 7. Given US sanctions against Iran no realistic of hope for IPI pipeline in the near future 8. If the US wants it can also make it harder for India to gain oil or LNG resources in other US friendly countries such as Qatar, Australia or Nigeria etc 9. India can pretty much kiss any hope of gaining a permanent UN seat goodbye for the foreseeable future 10. Just like PVNR backed out of nuclear test after preparing for it and then BJP went ahead with Pokhran-II, it is likely that another BJP govt would conclude the same deal and thus take all the credits at Congress's expense