India Has 2 Stage Thermonuclear Weapons

For some years my friend and long distance mental sparing partner, Ghalib Kabir, have been debating how far India has progressed in thermonuclear weapons.

Ghalib last argued here on March 22, 2024:

“My sense is Agni V very likely could sport 3 x 60-80 kt boosted fission warheads and a number of decoys. Not a bad start. I did hear 3 is likely the realistic number due to certain pertaining issues (likely miniaturization, warhead design-> yield related issues)

I know you set store by Israel or Russia sharing data for Indian 'cold tests'... however such a thing is unlikely as such a support would be 'too juicy' for known India baiters in the western and local 'non proliferation menagerie' to let go.”

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I (Pete) counter-argue:

I recognize it is part of the deal India made, with the Western powers, that India (at the public level) minimises its achievements in nuclear device progress.

This was one of the terms the West required when it generally accepted India, by 2010, as a semi-legal member of the nuclear weapons Club.

I have heard offline that there is no way India's top political leadership would permit India's nuclear program to lag 57 years behind India's largest opponent, China's. Meaning it is 57 years since 1967, the year China tested a three-staged thermonuclear device - see https://en.wikipedia.org/wiki/Test_No._6

Boosted fission weapons alone are simply old school, with several downsides. Two stage thermonuclear devices can be miniaturised far smaller - with higher yields - and permit more MIRVs than alleged 3 x 60-80 kt boosted fission warheads.

See https://web.archive.org/web/20171024045228/http://pib.nic.in:80/newsite/PrintRelease.aspx?relid=52814  
"The two-stage thermonuclear device, with a fusion-boosted fission trigger as the first stage and with the features needed for integration with delivery vehicles, was tested at the controlled yield of 45 kt and had the purpose of developing nuclear weapons with yields up to around 200 kt [on May 11, 1998 as "Shakti-I" being one of five nuclear tests at Operation Shakti/Pokhran-II] .

https://en.wikipedia.org/wiki/Pokhran-II#Specifications_and_detonation
Shakti I was “A thermonuclear device yielding 45 kt, but designed for up to 200 kt. The yield of this device was deliberately kept low in order to avoid civilian damage and to eliminate the possibility of a [dangerous and detectable] radioactive leak." 

Looking at https://en.wikipedia.org/wiki/Thermonuclear_weapon#India
"After the Pokhran-II tests, Rajagopala Chidambaram, former chairman of the Atomic Energy Commission of India said that India has the capability to build thermonuclear bombs of any yield at will." [Actual quote above from here https://www.nytimes.com/1998/05/18/world/nuclear-anxiety-the-overview-india-detonated-a-hydrogen-bomb-experts-confirm.html ]

 

Diagrams courtesy Brittanica.
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Conclusion

I’ve now come to the conclusion that we are both right. The “boosted fission” weapon Ghalib talks of was the Primary Stage setting off a Secondary Sage of an Indian Two stage thermonuclear device at the “Shakti-I” Test. See diagrams above.