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Sanjay Badri-Maharaj traces the story of Agni-V all the way back to the original Agni missile 

The test of the Agni-V missile in its final deliverable configuration on 26 December 2016 represents a major step forward for India’s strategic deterrence posture. Lost in the very legitimate emphasis on what the test means for India’s nuclear deterrent, is the fact the Agni-V represents the culmination to date of an evolutionary process in the development of India’s ballistic missile capability whereby one phase of development drew heavily on those that came before.

There is one important point to note: India has used depressed and lofted trajectories to simulate ranges on it missiles, none of which have ever been disclosed. There is a strong suspicion, with some foundation, that India has understated the range of its missiles from the Agni-II onwards. This trend continues with the words “more than” being almost a permanent prefix to range figures of Indian missiles.

The Agni Saga

The original Agni missile – formerly a “re-entry demonstrator” and which we can now term the Agni-TD – was tested on 22 May 1989. By its third test in 1994, the 2500 km range missile had achieved a demonstrated range of 1450 km with a claimed circular error probable (CEP) of 300m. However, what was the most remarkable aspect of this progenitor to the Agni missiles of the 21st century was that it was a hybrid, using the liquid-fueled Prithvi-1 missile as the basis for its first stage coupled to a solid fuel booster reminiscent of, but not identical to, the booster of ISRO’s SLV-3 launch vehicle. The Prithvi, which by 1994 had entered bulk production, was a reliable system with propulsion based on India’s stillborn “Devil” SAM project of the 1970s. This low-risk approach enabled India to develop an Intermediate Range Ballistic Missile (IRBM) capability at a relatively low cost, using proven technology.

However, it was soon realized that the Agni-TD was not a practical weapon owing in large part to its hybrid propulsion and the inherent problems of keeping such a system in a state of readiness or at least in a state of near-readiness. Moreover, it would appear that India, learning the lessons of the 1980s, decided against deploying its land-based deterrent in static hardened silos and opted for mobile systems. The Agni-TD was not a mobile system and developing its successor required not only an improved missile, but the development of a mobile launcher that could be deployed operationally.

The Agni-II

First tested on 11 April 1999, the Agni-II, with a range of anywhere between 2000 and 3000 km and with all solid-fuel propulsion. Tested to a range of 2300 km with a 1000 kg payload in 1999, the Agni-II established a pattern for Indian missiles – production and user trials would follow three consecutive successful technical trials. The 1999 test was followed by one on 17 January 2001 and a third on 29 August 2004. Production of the Agni-II followed thereafter but it was not until 2009 that user trials began, the first two of which were complete failures due to quality control problems during manufacture. However, on 17 May 2010, the first user trial from a production batch was completed followed by similar production batch trials undertaken by the Strategic Forces Command (SFC) on 30th September 2011, 9 August 2012, 7 April 2013 and on 9 November 2014. This means that the Agni-II has become the backbone of India’s IRBM force.

The Agni-II was India’s first viable production IRBM and is mounted on a rail mobile transporter-erector-launcher (TEL) with some suggestions that the TEL can be made road mobile as well. In either case, the TEL provides the Agni-II with flexibility in deployment as well as survivability. Furthermore, the system can be deployed within 15 minutes. The Agni-II marked India’s departure from liquid propellants to all solid-fuel systems. Furthermore, the Agni-II’s reputed CEP of between 30m and 100m at maximum range makes it an accurate system.

The Agni-I

In a curious twist, the Agni-II, which evolved from the Agni-TD, spawned the Agni-1. This 700km range medium-range ballistic missile (MRBM) was borne out of an operational necessity for a missile with a longer range than the Prithvi to serve as a deterrent against Pakistan. The Agni-II was effectively re-engineered to create a smaller, lighter and road mobile system that is both survivable and easily deployable. Since its first test in 2002, it has undergone a series of user trials from 2007 onwards, the last being on 22nd November 2016. While the missile itself is an achievement of note, the road mobile launch system should be considered of equal importance as it has evolved into the road mobile TELs for the Agni-IV and the Agni-V.

The Agni-III

At a glance, the Agni-III bears no physical resemblance to the Agni-II and is of a very difference configuration, renouncing the tall, slender form for a shorter but wider arrangement. With three stages, the Agni-III represents what might be termed an intermediate stage of missile development in India, part way between the Agni-II and the definitive Agni-V. Once again using a rail-mobile TEL, the Agni-III represents the largest missile to date that India has fired from such a launcher.

After a failed test in 2006, the Agni-III completed the now normal series of three consecutive technical trials on 12th April 2007, 7th May 2008 and 7th February 2010. Thereafter, the SFC conducted user trials of the system on 21st September 2012, 23rd December 2013 and 16th April 2015. Like the Agni-II, a CEP in the “two-digit” range (40m being suggested) was claimed. The Agni-III has a stated range of more than 3500km, but it bears a striking resemblance to the Soviet-era SS-20 IRBM, leading to the possibility that the range of the Agni-III could be as high as 5000km.

While in chronological terms, the Agni-IV succeeded the Agni-III, it is suggested that the Agni-III represents an entirely new missile family, unrelated to the Agni-II and its successor the Agni-IV. Rather, the Agni-III represents the precursor to the Agni-V which it closely resembles in size and configuration.

The Agni-IV

With a range of 4000km (or possibly more), the Agni-IV represents the successor to the Agni-II. Earlier known as the Agni-II Prime, the Agni-IV is no larger than its predecessor but has a significantly greater range and, being road mobile, is even more flexible and survivable than the Agni-II. This reflects a greater use of lighter composites and improved solid-fuel propellants and improvements to the guidance system ensure that even at maximum range, the Agni-IV retains a “two-digit” CEP.

While its first test in December 2010 was a failure, technical trials on 15th November 2011, 19th September 2012 and 20th January 2014, the latter in full user configuration, were deemed successful. Thereafter, the SFC commenced induction and carried out user trials on 2nd December 2014 and 9th November 2015. It is expected that the Agni-IV will supplement and then completely replace the Agni-II in production and become the mainstay of the Indian IRBM force. It is also noteworthy that there have been persistent rumours of a canister launched version of the Agni-IV being contemplated.

The Agni-V

While the first two launches of the Agni-V – on 19th April 2012 and 15th September 2013 respectively – were of the standard Indian uncanisterised missile, following the patter set with the Agni variants I through IV, the tests on 31st January 2015 and 26th December 2016 were of a canisterised system mounted on a road mobile platform. According to one report, by the usually well-informed Hemant Kumar Rout, Monday’s test was what might be termed a “contained test fire” to a range of 2500km, probably at a depressed or lofted trajectory to simulate a longer range. However, some analysis of the NOTAM issued prior to the launch suggests a splashdown zone between 4018km and 5123km from launch site. Given the fact that the Agni-V has already demonstrated a range of over 5000km, this should not be a cause for any concern.

However, what should continue to raise eyebrows is the persistent suggestion, backed by calculations based on flight time, speed and altitude of the Agni-V, that the range of the missile is in reality anywhere between 7500km and 8500km. It would be fair to term the Agni-V an intercontinental-range ballistic missile (ICBM) because the range of 5500 km is the demarcation line between IRBMs and ICBMs in the normal use of the term reflecting roughly the transatlantic distance between the Iberian Peninsula (or London) and the East Coast of the United States. IIndia varying trajectories to simulate much longer-ranges? This is a distinct possibility.

The Agni-V is so far, the ultimate evolution of the Agni family. It combines the road mobility of the Agni-I and Agni-IV with the configuration of the Agni-III but improves upon the latter redesigning the missile and making great use of maraging steel and composite materials to make the rocket motor. Moreover, improvements in the guidance system reputedly brought down the CEP to “single-digits”. With these improvements in place, the Agni-V is now ready to enter production and induction into the SFC which will then undertake user trials – starting with “user-assisted” trials and then, as with the case with Agni variants I-IV, the SFC will then take over subsequent trials.

Missiles and Warheads

Two issues frequently escape discussion when dealing with India’s missile arsenal – quantities and warheads.

The strength of the Agni missile force is obviously a closely guarded secret. It has been suggested that 334 and 335 missile groups which operate the Agni-1 and Agni-II missiles respectively possess 12 TELs each. While it has been stated that another group has been raised on the Agni-III, its designation is unknown and whether the TELs are accompanied by vehicles which carry reload missiles is equally unclear. It would be very odd if the total production of Agni missiles still remained in the low single digits per annum. It is in light of this that Dr. S. Christopher’s comments about 2015 production meeting only 20% of requirements is significant. One hopes that all necessary steps are being taken to enhance numbers.

As to warheads, even more speculation exists with experts such as Dr. Bharat Karnad being vociferous in suggesting only 15-20 kiloton warheads are deployed. However, this ignores two interesting revelations. Admiral Arun Prakash in 2009 (at the height of the controversy generated by Dr. Santhanam’s statements on the 1998 tests) stated: “In the midst of the current brouhaha, we need to retain clarity on one issue; given that deuterium tritium boosted-fission weapons can generate yields of 200-500 kt, the credibility of India’s nuclear deterrent is not in the slightest doubt.” More recently, an even more interesting comment was made by Dr. Avinash Chander in 2011 to the Business Standard newspaper in which he said: “Now we talk of [accuracy of] a few hundred metres. That allows a smaller warhead, perhaps 150-250 kilotons, to cause substantial damage.” In practical terms these comments suggest that the warheads fitted to the Agni missiles are boosted-fission designs with a yield of anywhere between 150 and 500 kilotons with the larger perhaps being on the outer extremity of being feasible. To discount these two statements coming from two totally different perspectives – one by a former Chairman, Chiefs of Staff Committee and the other by the former Director-General DRDO – would be folly to say the least.

What does the Agni saga tell us about the Indian ballistic missile program? Unlike almost any other DRDO project, the IRBM/MRBM/ICBM program has followed a path of constant product development and phased capability enhancement. This has meant that there is now a strong foundation in both design and systems engineering in respect of ballistic missiles with fabrication and construction facilities being able to deliver materials and products of sufficient quality. There has been a steady path of technological achievement – replacing liquid-fuels with solid, improved guidance systems for accuracy and improved materials for lighter weights and greater ranges. While there have been delays and failures, the DRDO ballistic missile program has done remarkably well on a limited budget. The Agni-V is reportedly due to be followed by the Agni-VI which would have an even greater range and multiple independently targetable re-entry vehicles (MIRVs) while a successor to the Prithvi and Agni-1, right now termed the Agni-1P, using technology from the Agni-IV is being designed. It is hoped that these two projects will be pursued with alacrity and intensity.