When US President George W. Bush and Manmohan Singh, the Indian prime minister, signed a controversial nuclear deal in July 2005, it was assumed the agreement would not survive the political Washington meat-grinder.

After all, Mr Bush was almost promising the moon – he would walk India into the nuclear clubhouse by getting Congress to change the law on non-proliferation and by persuading the international community to rewrite the rules of atomic commerce in favour of New Delhi.