By even talking about Agni-6, India may start a race it cannot win
The successful test-firing of Agni-5 ballistic missile on 26 December 2016 elicited a response from China. Asked to comment on the test-firing, Chinese spokesperson said that India should not disturb the strategic balance and peace in South Asia (between India and Pakistan). This was read in India to mean that China was rattled by India’s 5,000km range missile capable of hitting China’s heartland. To bring most of China into India’s ballistic missile range, India should, it was argued, unveil its Agni-6 missile with 8,000km range.
While the DRDO Chairman S. Christopher denied existence of the Agni-6 programme, his two predecessors, Avinash Chandra and V.K. Saraswat, were not so discreet. The DRDO had announced in 2013 that the ambitious Agni-6 would carry a 3-kiloton payload (three times more than Agni-5), have Multiple Independently Targetable Re-entry Vehicles (MIRVs) and reach ranges up to 8,000 kilometres. The DRDO chief in 2015, Avinash Chandra confirmed that the Agni-6 design was ready and would be put up for government clearance and funding after Agni-5 joined the Strategic Forces Command.
Assuming that the Agni-6 programme exists and would come up for government clearance soon, three questions that beg a reply are: does India need Agni-6 for its range and MIRV warheads capability; would DRDO have the technical expertise to make it within a defined time-frame; and, how would it disturb the strategic balance in South Asia.
If national security is the sole consideration, India does not need the Agni-6. Given China’s overwhelming superiority in nuclear and conventional war capabilities, and that nothing more than a border war is envisaged, why does India need Agni-6 when it has Agni-5 which can reach Beijing?
The Agni-5 single warhead could have three MIRV warheads. Since the weight of a 20-kiloton warhead is about 400 kilograms (from open sources), three MIRVs would mean a total of 1.2 tons; a little more than the one-ton warhead carried by Agni-5. A 20-kiloton nuclear bomb would completely devastate an area of 5.5-kilometre radius. The spread of nuclear radiation would go much further depending on weather conditions.
A MIRV is a ballistic missile which has multiple small warheads packed in a single warhead capable of hitting different targets simultaneously. In military terms, MIRVs provide two advantages: they enhance first strike capability, and a single thermonuclear or boosted fission weapon (in India’s case) is able to do greater damage.
Instead of Agni-6, the DRDO should concentrate on developing cruise missiles which are cheaper with far more operational utility than ballistic missiles. For example, Pakistan’s 500km range (can be fired up to 2,000km) subsonic Babur cruise missile with turbofan technology (acquired from China) is the game-changer because India does not have a comparable weapons system. India’s subsonic, two-stage, 1,000-kilometre range Nirbhay cruise missile, which has been test-fired thrice, has not been successful. Moreover, its propulsion system was procured from Russia in extremely limited numbers.
Regarding technical issues, there are two areas where DRDO would face major problems with no assistance from outside. The first relates to navigation and guidance. The Agni series uses strap-down inertial navigation system (SDINS) for guidance. None have seekers for terminal guidance. Unlike the platform (gimballed) inertial navigation systems which are intricately designed and used in intercontinental ballistic missiles, the SDINSs use dry-tuned gyros strapped to the missile body. The SDINSs have good reliability up to a 5,000-kilometre range, are cheaper than platform inertial navigation systems; are best employed against moving targets; and are unlikely to work at longer ranges even with nuclear warhead. Select countries, including China, have platform (gimballed) inertial navigation systems; India does not have them.
The other issue concerns stage separation. The issue in ballistic missiles, where within a split second the stage two propellant should start burning before the stage one motor burns off and falls to the ground, is an intricate and delicate affair. The DRDO has overcome the difficulty of three-stage separation in Agni 5 by use of a ‘velocity trimming module’ which helps the stage two propellant to ignite before the stage one motor falls off. This technique is unlikely to work in Agni-6 which, given India’s indigenous propellants, may need an additional stage.
It is well known that Pakistan has never shied away from matching India in both nuclear and conventional capabilities. For example, notwithstanding enormous US pressure to not conduct nuclear tests after India did its blasts, Rawalpindi did not relent. Moreover, Rawalpindi has offset Indian Army’s numerical advantage by developing expertise to fight on two battlefields — conventional and non-conventional. The answer to the Indian Army’s Cold Start Doctrine was found in the acquisition of tactical nuclear weapons. Once India signed the 2005 civil nuclear agreement with the US, Pakistan enhanced the production of its fissile material. To beat India’s purported indigenous ballistic missile defence capability it increased the variety and range of its ballistic missiles, and acquired the long-range Babur cruise missile from China. After India declared the need to build capabilities to fight a two-front war (where India assessed the real enemy would be Pakistan) in 2009, the Pakistan Army sought and developed interoperability with the PLA. And to neutralize a possible quasi-alliance between India and the US in the Indian Ocean region as well as India’s imminent sea-based deterrence, the Pakistan Army offered Gwadar Port to the Chinese Navy to have a free run in India’s backyard.
Given these realities, once India does test-firing of Agni-6 missile, Pakistan is certain to seek MIRVs capability to maintain strategic balance. Since China would give it that capability, its spokesperson was simply forewarning India about the things to come should it press ahead with Agni-6.