Indo-US Nuclear deal - Is the Left right?

I do not understand the Left parties. I never did and I have stopped trying to. What were the left parties doing when the Indian government started negotiations with the US government on the Indo-US nuclear deal? Were they sleeping? When the deal is in the final stage they wake up from their slumber and are opposing the deal.

They consider this as an opportunity to show how vulnerable the Indian government is without their support. I consider this as blackmailing. The failure of this deal will make Pakistan and China happy. I am not pro US or anti China. However, if the Indo-US nuclear deal is for the benefit of the nation then why not go for it. India's energy requirements have to be taken
care of. If the nuclear deal takes care of this then we need to go ahead and finalize the deal.

With friends like these (Left parties), the UPA (United Progressive Alliance) does not need enemies. I consider the Left parties stand on the nuclear deal as anti-national.