The Agni missile programme is a family of MRBM to ICBM ballistic missile systems developed by DRDO under the Integrated Guided Missile Development Programme. The land version of the nuclear triad, the Agni series of ballistic missiles are a part of the “credible deterrence” against India’s potential adversaries.

The Agni series of missiles were part of the Integrated Guided Missile Development Programme (IGMDP), which was an initiative of the Ministry of Defence to indigenously develop strategic and tactical missiles to meet India’s requirements. The nodal agency for the programme was the Defence Research and Development Organisation (DRDO) in partnership with other Indian Government labs and research centres. Dr Abdul Kalam, who later became the President of India, was one of the leading scientists of the IGMDP and later on oversaw the programme when he was Advisor to the Defence Minister. The programme started in the early 1980s and closed in 2008. However, work on certain missile systems is still on. IGMDP includes the following missile systems:

• Agni series of missiles to include ground based short-range ballistic missiles (SRBM), medium-range ballistic missiles (MRBM) and intercontinental ballistic missiles (ICBM)
• Prithvi short-range surface-to-surface missile system
• Akash and Trishul surface-to-air missiles system
• Nag missile anti-tank missile system
• Astra missile air-to-air missile system

The IGMDP has many successes to its credit like the surface-to-surface missile system. Akash is being inducted into the IAF. Army has also acquired it but for static role, Trishul was not successful and was thus foreclosed.

Agni Missile Programme

The Agni missile programme is a family of MRBM to ICBM ballistic missile systems developed by DRDO under the IGMDP. They are the land version of the nuclear triad. The family of Agni missile includes:

• Agni-I: An MRBM with a range of 700-1,200 km
• Agni-II: An ICBM with a range of 2,000-2,500 km
• Agni-III: An ICBM with a range of 3,000 plus km
• Agni-IV: An ICBM with a range of 3,200-3,700 km
• Agni-V: An ICBM with a range of 5,000 km range (under development)
• Agni-VI: ICBM with a 10,000 km range (under development)

Agni-I: In the backdrop of nuclear tests by India and Pakistan in 1998 and the Kargil War, it was felt by the Indian strategic planners that there is the requirement for a SRBM to fill the gap between Prithvi-II’s range of 250 km and Agni-II’s range of 2,500 km. Thus Agni-I was born from Agni II with a range of 700-1,200 km, carries a conventional payload of 1,000 kg or a nuclear warhead, is single stage and is powered by solid propellants. It was developed in a record time of 15 months and first tested on January 25, 2002.

Agni-II: Agni TD was a forerunner of Agni series of missiles. It was an IRBM with a planned range of 1,200 km and had its first launch during May 1992 which failed. After a few more failed attempts, it retired in 1994. Although Agni TD did not succeed, it became a base for subsequent development of Agni programme by providing critical technologies and design meant for long-range ballistic missiles. These were than optimised and further ruggedised. Other aspects like solid fuel chemistry, re-entry vehicle (RV) and avionics were also modernised. RV is made of a carbon-carbon composite material that is light and able to sustain high re-entry thermal stresses in a variety of scenarios. Agni TD programme helped in reducing the gestation period of Agni-II development. Agni-II is a two stage ICBM which uses solid propellant, has a range of 2,000-2,500 km and the post boost vehicle (PBV) is integrated into the missile’s RV. The PBV is a complex, exoatmospheric manoeuvrable vehicle that is used to position and deploy the RV, anti-ballistic missile countermeasure packages and other associated objects. The PBV contains guidance, control and thruster hardware that allows it to reorient and move in 3D while it flies along its ballistic arc. The Agni-II requires a preparation time of only 15 minutes before launch as it is always in a ready-to-fire mode. The previous generation of missiles required almost half a day of preparation before they could be launched. The Agni-IIAT is a more advanced version of Agni-II which provides a better range and operating regime. The Agni family of missiles uses a strap-down inertial navigation system (INS) for flight control and navigation. Necessary inertial sensors were indigenously developed for the purpose, including laser rate gyros. An INS is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references.

Agni-III: Agni III uses solid propellant in both stages. Agni-III was tested on July 9, 2006, and after the launch, it was reported that the second stage of the rocket did not separate, and the missile had fallen well short of its target. Agni-III was tested successfully on April 12, 2007 and May 7, 2008. The successful tests validated the missile’s operational readiness. With a range of 3,500 km, it had a reach across most high-value targets of India’s potential adversaries. It has a warhead of 1.5 tonnes. The circular error probable (CEP) has been reported as of 40 m, which makes it one of the most accurate strategic ballistic missiles of its class. A lower CEP makes the ballistic missile highly accurate and increases the kill efficiency of the weapon. The implications are that nuclear warhead of a smaller yield can be more effective when fired from Agni-III than a nuclear head of higher yield due to greater accuracy of Agni-III. Thus India can deploy larger nuclear forces using lesser fissile/fusion material.

Agni-IV: Agni-IV was earlier known as Agni II prime and was tested on November 15, 2011. It has a range of 2,500-3,500 km and bridges the gap between Agni II and Agni III. Agni IV is equipped with state-of-the-art technologies including indigenously developed ring laser gyro and composite rocket motor. It’s a two-stage missile powered by solid propellant, with a warhead of one tonne. It is designed to increase the kill efficiency along with a higher range performance and can be fired from a road mobile launcher. A day after the successful launch of Agni-IV missile, DRDO Chief V.K. Saraswat stated that all the technologies and critical systems used in Agni-IV worked perfectly and hit the target. Scientists will use the same package for launching Agni-V. He said Agni-IV has propelled India into the elite League of Nations having similar class of missiles including the US, Russia and China. The indigenously developed technology produced by Indian industry included ring laser gyros for navigation and accuracy, composite rocket motor, high performance onboard computer with distributed avionics architecture and a full digital control system which controls and guides the missile during its flight. Highlighting the importance of Agni-IV test, Saraswat said, “This missile is lighter, more compact, difficult to detect by radars and counter-ballistic missile measures, and is world class. While Agni-II is nearly 47 tonnes, Agni-IV is 20 tonnes, thereby giving us more operational freedom. We are now manufacturing carbon fibres, titanium, composite material and state-of-the-art navigation systems and no technology control regime can stop us now from testing ICBMs and similar strategic weapon systems.”

Agni-V

Agni-V is a solid fuelled ICBM which has a planned range of 5,000 km and is currently under development. The tests are likely to start during the early part of this year. It has been designed by adding a third composite stage to the two-stage Agni-III missile and composite material has been used extensively to reduce its weight. Agni-V would be canister launched for ease of transportation and launching. After the successful launch of Agni-IV, Saraswat had said that “Agni-V missile is currently undergoing integration and we may test fire it by the end of February next year. It is right on schedule and the successful test of Agni-IV will prove to be a building block in the development of this missile.”