High time for a 10,000-km range ICBM

by Jan 23, 2021Defence & Foreign Policy0 comments

Renowned Indian philosopher Kautilya had once very aptly stated, “The power of a king lies in his mighty arms. Security of citizens at peacetime is very important because state is the only saviour of men and women who get affected only because of negligence of the state.” At a time when expansionist aspirations of some rogue nations are on the rise all across the world, Kautilya’s quote is very much valid and applicable in totality, even in the third decade of the 21st century.

Prime Minister Narendra Modi’s strategic vision is to see India emerging as a first rung global military power by the middle of this new decade. Maintaining an effective intercontinental-range nuclear deterrence by deploying Agni-V and Agni-VI missiles will play a key role in fulfilling this Indian dream.

While the Agni-V, the nuclear capable intercontinental range ballistic missile (ICBM), has undergone seven successful test flights since 2012, there has been very little movement on the much-awaited Agni-VI missile project. After Agni-V’s maiden trial on April 19, 2012, former DRDO Chairman, Dr Vijay Kumar Saraswat had very clearly stated that India had no intention to cap the Agni missile programme and that there would be more missiles in the Agni series as a follow-up of Agni-V in the coming years. The Agni-V has an effective range of almost 5500 kms with a 1.5-tonne nuclear warhead. A basic law of physics is that due to gravity and momentum, there is an inverse relationship between the weight of a warhead and the range of a missile. If the same rocket boosters of Agni-V (better with a slow burning propellant) for the heavy load is used for a lighter load amounting to a 500 kg warhead, the range of the missile can be enhanced up to 10,000 km. So, by this theory, the Agni-V is already a 10,000 km-class ICBM albeit with a less powerful warhead. And this is one of the prime gaps in India’s nuclear deterrence which the Agni-VI is supposed to plug. Agni-VI is expected to have a range between 6,000 kms and 8,000 kms with a 3-tonne nuclear payload, and a range between 10,000 kms and 12,000 kms with a lighter 1.5 tonne package. Guidance system of Agni-VI will include inertial navigation system with Ring laser gyroscope, optionally augmented by IRNSS (Indian Regional Navigation Satellite System) along with terminal guidance with possible radar scene correlation (this is a kind of terrain contour mapping which will improve the accuracy of missile).

In 2011, IAF’s former Chief of Air Staff, Pradeep Vasant Naik, who was also the head of Chiefs of Staff Committee had vehemently argued in favour of broadening India’s nuclear striking capabilities beyond the immediate neighbourhood. The higher range of Agni-VI will bring at least four of the capitals of major world powers within India’s strike envelope. A 10,000 km-plus range will increase India’s flexibility which is very important for an effective deterrence and will also enable the country to hit Chinese ballistic missile submarines (SSBNs) and warships attempting to hide as far out as the Southern Indian Ocean and Central Pacific Ocean. This is assuming India develops more accurate ICBM guidance systems (on the lines of China’s DF21D anti-ship ballistic missile) against warships and submarines. India must wish that the Agni-Vi should have the minimum range of 8000 kms (equivalent to China’s JL-2 submarine-launched ballistic missile) which will make the ICBM programme worthy of its stature.

Agni-VI is supposed to be capable of carrying up to 10 nuclear/ thermonuclear warheads in MIRV (Multiple Independent Re-entry Vehicle) and MaRV (Manoeuvrable Multiple Independent Re-entry Vehicle) configurations. The rocket may also have the capability to carry light decoys and chaffs to beat the most formidable anti-ballistic missile systems and to confuse hostile radar defences. As India has reportedly developed a deadly arsenal of double-staged thermonuclear fusion devices and single stage boosted-fission bombs, each MIRV warhead may have explosive yields of up to 250 kilotons, thus capable of wiping out entire metropolitan areas and vaporising tens of millions of people with a single strike. Having a gross weight of up to 70 tonnes, Agni-VI is supposed to be a four-stage rocket which will also enable India to launch military satellites into low earth orbit (LEO) during contingencies, thus also validating its FOBS (Fractional Orbital Bombardment System) capability. Renowned strategic experts like Bharat Karnad, Brahma Chellaney and Rakesh Krishnan Simha have repeatedly argued in the past that India must develop a global striking capability with a credible ICBM force in the near future.

“It is high time for India to develop genuine ICBMs with 10,000+ kms range. The Agni-VI project should be immediately approved for development. Geopolitical pressures faced by a country are always the results of a nation’s will and its strategic vision. The incumbent union government must show the spine to stand up to such pressures without which India can never aspire to become a great power”, says Bharat Karnad, Research Professor at the Centre for Policy Research and a popular national security expert. A large ICBM force consisting of Agni-V and Agni-VI missiles will ensure a very strong security shield for the country in the strategic level battlefield and will severely deter big powers from attempting Balkanisation of India during future conflicts. While the erstwhile UPA-1 and UPA-2 governments were considered as ‘pacifist’ by many policymakers, it is high time for the incumbent NDA-3 government to prove its political will by swiftly approving the Agni-VI programme and by test launching the first prototype over the coming years, thus pushing India into the elite league of military superpowers like USA, Russia and China. Such a capability will give India tremendous diplomatic leverage at global high tables. Without a credible ICBM force, India will always be looked upon as nothing more than a subcontinental bully- a country that aspires to play hardball with the giants but ends up relegated to the minor league. The ball is now in the ruling dispensation’s court.

Thermonuclear warhead options for India

After the ground shook under the hot desert sands of Pokhran on May 11, 1998, India had officially declared herself as a ‘full-fledged nuclear weapons power’ with three simultaneous nuclear blasts. Two more detonations followed on May 13, 1998 thus ending the series of planned tests. Soon after the series of explosions was over, eyebrows were raised in Western scientific and media circles regarding the blast-yield of one of the underground detonations. The thermonuclear weapon prototype which was reportedly detonated at an explosive yield of around 45 kilotons, soon found itself in the middle of the controversy. The device reportedly had a design yield of up to 200 kilotons and was dubbed as a fizzle by some Western experts. But the country’s scientific establishment later conducted an official press conference in which eminent scientists- Dr APJ Abdul Kalam and Dr Rajagopalachari Chidambaram clarified that the thermonuclear weapon performed on expected lines and that the blast yield of the Shakti-1 thermonuclear device was deliberately kept low taking into consideration the terrain and topography of the area and the test site’s proximity to Khetolai village.

BARC (Bhabha Atomic Research Centre) officially clarified that Shakti-1 was a highly compact thermonuclear device which used a sophisticated fusion-boosted-fission trigger as the primary stage and a Tritium cylinder as the secondary stage. In order to put all controversies to rest, BARC also executed a radiochemical analysis of soil and rock samples extracted from the thermonuclear blast site. The post-shot radioactivity measurement report on the samples says- “The signatures of the fusion reaction are activation products due to 14 MeV neutrons, such as, 54Mn, 22Na, 58Co, 46Sc, as marked in the gamma-ray spectrum. The estimation of 14 MeV neutron yield from the measured radioactivity of these products requires the knowledge of the amount of the target elements present at the site of the event and the reaction cross sections. The two major radionuclides which could be assayed in most of the samples were 54Mn and 46Sc. Although the fission neutron spectrum has a high energy tail, the total number of neutrons produced by fusion fraction being much larger, the majority of the high energy neutrons can be attributed to fusion neutrons. The possible sources of error in the measurement of fission yield are: assay of radioactivity (5-7 percent); nuclear data such as half-life, gamma-ray branching intensity and fission yields (8 percent); and the error in integration which arises mainly due to the error in Rc (15 percent). In the assessment of fusion yield, the sources of errors are uncertainty in the elemental composition of the surrounding rock and its effect on the neutron spectrum used in the Monte Carlo simulations of the activity. The propagation of these errors leads to an overall error on the measured yield which is around 20 percent. Thus, it is concluded that the total yield of the thermonuclear device is 50 + 10 kT.” While the report confirms that 14 MeV neutrons were found as a result of initialisation of the fusion reaction from the secondary stage of the bomb, the total explosive yield has been disputed by senior scientists like Dr K Santhanam and Dr PK Iyenger who have argued that the total yield of the thermonuclear blast didn’t exceed 20 Kilotons. This once again puts into doubt the union government’s claim of having a deployable thermonuclear deterrence in operational configuration.

The story of India’s Hydrogen Bomb programme (thermonuclear bombs) dates back to the late 1980s when scientists found an easy way to extract Tritium gas (an isotope of Hydrogen) from heavy water. Unlike nations like United States and Russia which used light water as a moderator in their nuclear reactors, the Indian nuclear program was primarily based on heavy water. It is quite evident that the heavy water contained high doses of radioactive Tritium which exposed reactor workers to potential health hazards. So, an initial attempt was made to extract the Tritium component through water distillation. But soon, the process was abandoned as the Tritium collected through the process was in liquid form and proved to be extremely risky to handle and store.

So, scientists found an alternative way to extract the Tritium through chemical exchange process followed by cryogenic distillation. The Tritium extracted through this innovative was stored in gaseous form and was 90 percent radioactive which rendered it highly useful for fabrication of thermonuclear weapons. Thus, what was dubbed primarily as an effort by scientists towards making the nuclear reactors safer by eliminating Tritium from heavy water, proved to be a boon for manufacturing of Hydrogen bombs. A pilot detritiation plant was also established in Kalpakkam nuclear research reactor. As the new process for extracting Tritium proved to be quite economical in comparison to the traditional process, stockpiling of Tritium became an easy task. As the Indian way of extracting Tritium from heavy water proved to be much cheaper than the age-old accelerator process used by the Americans, the country got the highly enriched Hydrogen’s isotope at negligible additional costs. Moreover, more electricity production by Indian nuclear reactors also ensured that large quantities of Tritium was extracted and stored for the country’s thermonuclear bomb program. The country which was once a gross importer of heavy water became a net exporter of the same compound by the late mid-1990s.

It is estimated that India had assembled the first prototype thermonuclear device by 1995 in preparation of a test under the then union government led by erstwhile Prime Minister Narasimha Rao. But as American reconnaissance satellites hovered over the Pokhran firing range and the images of the test preparations circulated in the Western media, the Indian government had to cancel the test under American pressure. The Shakti-1 thermonuclear device was finally fabricated in test configurations and eventually exploded in 1998. While it is a well-known fact that no nuclear power has been able to successfully test a double-staged thermonuclear weapon in the very first attempt, the Indian test and the ensuing speculations about the blast yields raises doubt over the deployability of the capability in operational warhead configuration atop Agni series of medium-range, intermediate-range and intercontinental-range ballistic missiles.

While questions have been repeatedly raised on India’s capability in possessing and fielding a credible thermonuclear deterrence, the country has reportedly deployed a small thermonuclear arsenal through ballistic missiles after the completion of Pokhran-2 series of tests. Renowned nuclear scientist Dr Anil Kakodkar while interacting with journalist- Karan Thapar during a media interview after the 1998 tests, confirmed that India has already fielded multiple hydrogen bombs in operational configuration. But the million-dollar question about India’s capability in potentially achieving massive thermonuclear yields during nuclear strikes without actually testing those devices in full design yields during field trials still carries an air of ambiguity. While renowned strategic experts like Bharat Karnad has repeatedly stated publicly that India should resume thermonuclear testing for mastering the double staged fusion design (Teller-Ulam design), there are others like R Prasannan who argue that India has already developed advanced supercomputer simulations and that bigger bombs with higher yields can be confidently developed and deployed based on the data gathered from previous tests. Strategic experts like Sanjay Badri Maharaj also argues that the question whether India has deployed a credible thermonuclear deterrence, is somehow irrelevant as the Shakti-1 device exploded on May 11, 1998 had a boosted-fission device as the first stage. A boosted-fission device is equivalent to a compact hydrogen bomb and will serve the purpose of a credible thermonuclear deterrence in the modern-day strategic level battlefield when deployed onboard long-range ballistic missiles.

As India’s deterrence requirements evolve over time, it is quite evident that the country must develop an effective and significantly large arsenal of thermonuclear weapons. The thermonuclear devices with adjustable and variable yields will make good use of India’s limited stockpile of fissile materials and will effectively act as a force multiplier. With increasing precision in the design and development of lighter and compact payloads, the thermonuclear warheads can be easily deployed onboard Agni-V and the upcoming Agni-VI Intercontinental range Ballistic Missiles (ICBMs) in the form of MIRVs (Multiple Independent Re-entry Vehicles) and MaRVs (Manoeuvrable Multiple Independent Re-entry Vehicles) which will massively boost India’s long-range striking capabilities deep inside enemy’s heavily populated urban centres.

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