Ahead of finalizing the Indo-US nuclear deal, the US has categorically stated that any future nuclear test would impel the discontinuation of nuclear energy assistance to India. Contrary to the 18 July 2005 Indo-US Joint Statement, the nuclear deal has become intertwined with the strategic aspects of India's nuclear weapons capability. The deal is important for India, but its fate is now contingent on India's stance on future nuclear tests.

After the May 1998 tests, Dr. R Chidambaram had declared that India did not need to conduct any further nuclear tests. A pertinent question then arises whether India has developed warheads that need no further design improvements. The 1998 test results were however, controversial with different yields being cited by different sources. India can hardly claim, therefore, to possess an effective nuclear deterrent. With the passage of time, technology scales new heights in military capabilities, as is evident from the sophisticated miniature nuclear bombs being designed in the US. It would therefore be unrealistic for India to remain satisfied with a stagnant deterrent capability.

It is argued that a credible nuclear deterrent can also be achieved through laboratory tests or computer simulation exercises. This is debatable. In a low-yield "sub-critical" test, no critical mass is formed and no self-sustaining chain reaction occurs. Weapons developed by laboratory or sub-critical tests will not infuse confidence among political and strategic communities. In a "thermonuclear" test, the implosion causes a supercritical mass to be formed for an extremely small time interval, which is not maintained long enough to permit the device to achieve its full explosive yield. During the CTBT discussions, both the US and UK insisted on retaining the option to conduct nuclear tests with nuclear yields up to four pounds of TNT equivalent, but under the present agreement, Washington wants to restrict India to a one pound TNT limit. This would make it almost impossible for India to conduct meaningful tests to upgrade its nuclear arsenal.

Future nuclear tests are crucial for ensuring the safety and reliability of existing nuclear arsenals and making design improvements for higher yield and reducing the yield-weight ratio of nuclear warheads in the future. The US after several tests has developed state-of-the-art nuclear bombs that are easily transportable. Testing is also important so that the existing weapons inventory do not become obsolete. It provides a valuable database which is useful for the design of nuclear weapons of different yields for different applications and different delivery systems. Testing ensures modifying or compacting the present warheads for building a credible nuclear deterrent.

The need for India to keep the nuclear testing option open is further justified because its nuclear doctrine is based on the cardinal principle of no-first-use and minimum nuclear deterrence. India's nuclear doctrine has led to its maintaining its nuclear arsenal in a de-mated and de-alerted state. Its nuclear posture is designed to protect its national interests and safeguard the national security. The credibility of this posture derives from India effectively communicating its resolve to its adversary, viz. that any nuclear attack will be reciprocated with a symmetrical response. To achieve this objective, India requires modern state-of-the-art weapons, tried and tested, which could deter any belligerent adversary from contemplating an attack on India.

It is important to remember that nuclear technology cannot be bought off the shelf. Only constant testing will help devise weapons of maximum yield and capability based on advanced design technology. It is not enough to develop a new weapon without testing and have confidence that it will work effectively. What is important is that the soldier must have faith in the weapons provided to him. India paid a high price in the Kargil War with the loss of hundreds of its soldiers due to their having heavy antiquated weapons that they had to carry across difficult terrain. Future tests are also important to provide reassurance to the people of India that their national interests will be promoted and protected.

After the May 1998 tests, India was under stringent sanctions under the existing US laws. If India is to conduct any nuclear tests in future, India would again be subject to sanctions by the US. The legal situation is thus clear. After the May 1998 tests, India had announced a unilateral moratorium on nuclear testing to reassure the global community, as also to the ideal of global nuclear disarmament. This is a voluntary stand, which was reiterated in the July 2005 agreement. However, India's voluntary moratorium cannot foreclose the option for a future government to test if national interests so demand. India cannot convert its unilateral voluntary moratorium into a bilateral legality.