Hans Kristensen, director of the Nuclear Information Project at the Washington-based Federation of American Scientists, is in the news for an academic paper he has co-authored with Robert Norris, claiming that Pakistan has ramped up its nuclear arsenal with sophisticated bomb designs, and with its delivery systems directed against India. He spoke to Ashish Kumar Sen on the Pokhran-II controversy. Excerpts:
Do you agree with former DRDO scientist K. Santhanam’s assertion that Pokhran-II was a fizzle rather than a big bang?
Perhaps not a fizzle, but certainly not the 45-kilotonnes claimed. But an assessment is complicated by the fact that the tests on May 11, 1998, were conducted simultaneously.
On what basis do you say that the thermonuclear device could not have yielded 45 kilotonnes?
Indian scientists initially said the May 11 tests were 43, 12, and 0.2 kt. Later reports said 45, 15, and 0.2 kt. The three claimed explosions were simultaneous, but the total claimed yield of 45-60 kt yield is not reflected in the seismic signal (mb) of 5.2, which indicated a total yield of only 5-20 kt.
The seismic readings of May 11 blasts were said to be different in the West and in India. Is this possible?
Seismic signals change when they travel great distances through the earth, but seismologists compensate for this when they interpret the data. So, this is not something that would effect the yield assessment.
Based on your findings about Pokhran-II, do you believe India has an adequate thermonuclear (hydrogen bomb) deterrent?
I doubt India has a “thermonuclear” deterrent, but one that consists of single-stage (probably boosted by tritium) warheads.
Thermonuclear device tests conducted by countries such as China produced yields in the megatonnes. Is it possible for India to miniaturise the thermonuclear device to get a 45-kilotonne yield?
Theoretically yes, but why go through the trouble of developing a thermonuclear device if you only want 45 kilotonnes? Thermonuclear devices are for hundreds of kilotonnes—even megatonnes, not tens of tonnes.
So then, is a test that yields 45 kt considered a success?
Not a very successful one, if it’s a thermonuclear device.
Is it possible to attain success with just one thermonuclear test?
If success means producing a large bang, then yes it is possible. But if it means the weapons engineers and the military having sufficient confidence in the design, then probably not.
Does India need to conduct further thermonuclear tests to remove doubts raised by scientists?
If India wants to develop (and have confidence in) two-stage thermonuclear warheads, then it probably needs more tests, but if the goal is to have a credible nuclear deterrent then it doesn’t need more tests. The credibility is not about the type of warhead but whether India has shown that it can bring a nuclear device to explosion and that it has the delivery vehicles to deliver the warhead to its target.