A year after the US and India reached an historic agreement on nuclear trade, some Indian nuclear scientists are saying their country has to do more tests. Why? Despite the worries this will give non-proliferation supporters, India needs to ensure it has a "credible nuclear deterrent" in its arsenal, according to two retired nuclear scientists. One of them K. Santhanam, who coordinated India's nuclear weapons programme when the country conducted nuclear tests a decade ago, said its original thermonuclear device test was actually a dud. Santhanam’s call comes even as support for a universal test ban is gaining some traction after Obama’s UN speech. His disclosures have enraged the Indian military and international security community as well. This apparently comes from a concern that Indian Prime Minister Manmohan Singh is prepared to support Obama’s push for comprehensive test banning and a need to keep Indian options open. Santhanam’s call is not unique. The former head of India’s Atomic Energy Commission has said, “nobody makes a weapon out of a single test”. Five Indian tests in May 1998 prompted Pakistan to conduct its own tests. Heads up China and Pakistan?