Abish, Which agreement between India and any other country is made published to the public. Vajpayee and Mushraf did agra summit and signed an agreement, Who knows the content and has the copy. These all are confidential ones. Everything cannot be published to everybody especially when things to matter to nuclera reactors.
So don't go by the word of Karat and gang. There only opposition was it was USA on the other side.. Its not India alone who signed such treaties, even Left's mentor China also signed such a deal with US and reports are there that this deal is much better tahn China's deal and thats why China is opposing it.