A well-known 1985 West German intelligence report cited one agent's unconfirmed report that the brief from the Rajiv Gandhi government to BARC was to "continue working on the development of a nuclear fusion weapon (hydrogen bomb)." BARC was to ensure that "within two months of a Pakistani test, the second Indian test should be carried out. Such an Indian test should simultaneously be used for the development of a fusion explosion."
During the 1980s, India established an inertial confinement fusion programme to study high-density physics associated with thermonuclear weapons. In 1989, then CIA director, William H Webster, told the US Senate that several other indicators pointed to India's interest in acquiring a thermonuclear weapons capability, including the purification of lithium, production of tritium, and the separation of lithium isotopes.
Although several experts in the US nonproliferation community believed that India had the scientific expertise to build a hydrogen bomb, the critical breakthrough in a thermonuclear weapon design came in the mid-1990s. According to Indian scientists, if India had tested in 1982-83 as planned originally, it would have involved the validation of miniaturised fission and boosted-fission designs.
Weaponisation, according to India Today, involved four steps. Nuclear devices were miniaturised to facilitate delivery from aircraft. Weapon designs were ruggedised for field deployment and transport. Mechanical and electronic arming and safing systems were installed in weapon systems to prevent unauthorised or accidental detonations. And by 1989, the Indian air force modified combat aircraft and perfected techniques for the aerial delivery of nuclear munitions.
According to new information released by the Indian government, the process of weaponisation was divided between BARC and the Defence Research and Development Organisation. BARC worked out concepts related to the "long shelf life of the nuclear components" and the "optimisation of the weight-to-yield ratio." It was also responsible for the fabrication of fissile material into suitable shapes. DRDO labs worked to weaponise the nuclear devices to military specifications. This involved the design and development of the high-explosive lenses to be used in the implosion device, "high-volt trigger systems, interface engineering, and systems integration to military specifications." Three other labs, according to the science advisor to the defence minister, A P J Abdul Kalam, contributed to the "arming, fusing, safety interlocks and flight-trials."
Weaponisation was also accompanied by the establishment of a rudimentary command, control, and communications structure to manage contingencies arising from nuclear war planning. In the winter of 1990, the former director of DRDO, V S Arunachalam, apparently told Harvard academic Stephen P Rosen, that the civilian leadership in New Delhi fought a difficult struggle with the military over custody of nuclear weapons. That struggle was finally resolved in favour of civilians. Apparently, the military was told neither of the exact number of nuclear weapons that India might have, nor how they would be employed in a nuclear war. But the civilians drew up detailed instructions to deal with problems in the absence of a formally articulated nuclear doctrine. These instructions were given to a certain theatre military commander with instructions to open them in the event of a nuclear war.
In his book, Societies and Military Power: India and Its Armies, Rosen quoted Arunachalam as saying, "If New Delhi goes up in a mushroom cloud, a certain theatre commander will go to a safe, open his book, and begin reading at page one, paragraph one, and will act step by step on the basis of what he reads...." Arunachalam later denied making that statement. However, Abdul Kalam recently affirmed that India had indeed instituted measures to manage its incipient nuclear weapons capability. Kalam told a press conference on May 17, 1998 that "the [nuclear] command and control structure which had been existing in various forms is now being consolidated."
Besides building air-deliverable fission weapons, BARC also focussed attention on the design of light and compact warheads for ballistic missiles. In the late 1980s, an Indian scientist told a Western observer that BARC had designed a light fission warhead with a mass of 200kg. In this context, it should be noted that analysts had long doubted DRDO's assertion that the Prithvi and Agni would deliver conventional munitions. Cost-benefit analysis of the range, payload, and accuracy indicated that ballistic missiles of that class only made strategic sense if deployed in a nuclear mode.
In July 1989, the Washington Post reported that concerns about BARC's interest in ballistic missile warheads had caused the Bush administration to deny the sale to India of a $ 1.2 million Combined Combined Acceleration Vibration Climatic Test System with a force-level capability of 545 kg. Also known as the "shake and bake" system, a CAVCTS can be used to test re-entry vehicle components for their ability to withstand the heat and stress during missile flight.
Nevertheless, India persisted in its quest to develop re-entry vehicle technology. Between 1989 and 1994, India conducted three Agni flight-tests. Two of these were successful and validated the re-entry vehicle technology. According to DRDO sources, results showed that the missile's composite carbon-carbon nose cone had ablated as designed. While outside temperatures during re-entry reached 3,000°C, temperature inside the re-entry vehicle did not exceed 40°C. Even more importantly, the payload comprising the autopilot, dummy warhead, its arming and fusing systems and the inertial navigation system survived the stress of re-entering the Earth's atmosphere.
Writing in the November 1996 issue of Jane's International Defence Review, Pravin Sawhney, a former artillery officer in the Indian army, described in precise detail as to how DRDO proposed to simulate flight-tests for nuclear warheads over land to ensure that their subsystems functioned in accordance with design parameters. In the absence of permission to conduct "dynamic" tests, Indian scientists proposed that a non-fissionable core be used to replace the fissile material inside the dummy warhead that would be dropped from a helicopter over a test-range.
By examining telemetry data generated during flight and recovering the warhead debris, scientists would be able to determine whether the safety and arming systems unfolded in the designated sequence, whether the fuse functioned at the desired height of burst, and whether the non-fissionable core imploded uniformly.
Whether DRDO actually conducted such tests is still unclear. However, referring to weaponisation of ballistic missile warheads, Abdul Kalam admitted recently that India had "tested the size, weight, performance, and vibrations [of missile warheads]." He further acknowledged that "we have been doing this for quite some time."
This evidence indicates that the May 1998 tests marked the "culmination" of the weaponisation process. Cognisant of India's nuclear neighbourhood, successive governments sought to provide insurance against nuclear blackmail. India's "option" strategy was not a policy of bluff. If current reports attributing the weaponisation decision to the Rajiv Gandhi government are true, then India actually exercised its "option" as early as 1988.
By authorising the tests, the BJP has brought India's secret nuclear weapons programme out of the closet. Earlier governments invested in a policy of existential deterrence. The BJP has taken that policy a major step further authorising the validation of a series of weapon designs. Simultaneously, it has declared its intention to operationalise deterrence by integrating weapons into the armed forces, formally articulating a nuclear doctrine, and institutionalising a command, control, and communications structure. These constitute the first steps on the road to a strategy of nuclear war fighting.