Though Indian scientists have publicly assured the nation that after placing 14 nuclear reactors under International Atomic Energy Agency safeguards -- including the six reactors that are already under safeguards --the country's full security requirements would be met in terms of a credible minimum deterrent, a few strategists are still pressing the issue.

Their point is: How could India escape capping its nuclear capacity when half of its 16 Pressurised Heavy Water Reactors -- PHWR -- are under safeguards? Those who consider that too many reactors have been given away to international safeguards, project the impression that all PHWRS were intended to support the strategic programme and hence their reduction will inevitably result in the arsenal being capped.

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Is this a valid projection? The PHWR produces plutonium. But that is not weapon grade plutonium but what is called reactor grade plutonium which is a mix of two plutonium isotopes -- plutonium 239 and plutonium 240. For weapons-making, scientists prefer plutonium 239 with contaminant 240 not being more than 7 percent.

In India only the CIRUS and Dhruva nuclear reactors are normally run for weaponisation purposes. All other PHWRS are normally run for power generation. To run them economically they should be run at high or normal' burn-up'. For a PHWR to produce weapons grade plutonium, it should be operated at a low `burn up' and the fuel rods withdrawn early before the presence of contaminant plutonium 240 exceeds 7 percent.

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The Americans as far back as 1962, and the British before them in 1953, proved that reactor grade plutonium can be made to explode. In our 1998 nuclear tests, our scientists also used reactor grade plutonium in a sub-kiloton explosion.

But that does not mean our scientists and our military will be content to have the reactor grade mixture of plutonium 240 and plutonium 239 as their normal basic fissile material for the weaponisation programme. The problem with reactor grade plutonium as weapon making material is that in technical terms, it has prefissile tendency and cannot normally make a weapon with predictable explosive yield.

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In other words one cannot be sure whether a weapon with high PU240 content will explode with the expected yield or a much lower yield. Therefore, those who contend that because one of our tests resulted in a nuclear explosion all PHWR-yielded plutonium can be used to make weapons of predictable yield, are not entirely correct.

If the NDA government had been worried about the Fissile Materials Cut off Treaty being concluded in the near future, then the logical course for them was to have run our PHWRS not in power generation mode but on low burn up to produce weapon grade plutonium.

Had this been done, each nuclear power station would have produced four times the weapon grade plutonium as Dhruva. Presumably this was not done. Otherwise, even the worst critic of the Indian weapons programme in the US would not talk of India having a mere 95-100 weapons.

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There also would not have been so much anxiety over India not being able to reach the credible minimum level of fissile material, expressed by some NDA leaders, who failed to initiate all necessary efforts to reach that level at a very early date.

A great deal of mystery shrouds the number needed for a minimum credible deterrent. While it is reasonable to argue that this is not a number but a dynamic concept at the beginning of the build-up of an incipient arsenal like India's, the same argument can be seen as justifying an arms race if it is resorted to eight to ten years after the build up started. Or, the argument that 1600 MW capacity for weapon production that has been kept out of safeguards is not adequate to sustain our strategic programme.

This capacity should have been taken into account by the National Security Adviser, the Chief of Staff, the Principal Scientific Adviser to the Prime Minister (who continues from the NDA regime) and the chairman of Atomic Energy Commission, who is also an NDA appointee. They are not strangers to the exact number of credible minimum deterrent needed.

The credible minimum deterrent number refers not only to nuclear warheads but also their delivery systems and credibility. It also means matching the reprocessing capability to weapons grade fissile material available and the weapon fabrication capability.

Over the six years the NDA was in power after the nuclear tests the pace of build-up of the nuclear arsenal should have been planned by it. What were the strategic assumptions on the basis of which the NDA determined that pace? Has the international strategic situation since worsened?

The general assessment is that with India enhancing its relationship with the US, establishing a partnership with Russia [Images] and improving our dialogue with China, the global strategic environment is improving from the Indian point of view.

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The minimum credible deterrent is anchored on the survivability of adequate retaliatory arsenal. That was the reason why the doctrine included the strategic triad. The same NDA leaders who pooh-poohed the concept of strategic triad, because of the disapproval of some American officials and think tanks, now talk about the risk of our arsenal being capped at some indefinite future and in unforeseen contingencies.

One can understand if those who are worried about the arsenal being capped were to advocate what steps should be taken to step up the build-up of weapons grade plutonium. Instead, they are focusing on the number of reactors to be brought under safeguards only because they have to oppose the deal for the sake of opposition.

In any case, having more reactors outside safeguards and merely producing reactor grade plutonium will not enhance our security. This attitude is similar to that of our political leadership of the last five decades who never understood that short and limited wars can be fought only with weapons and ammunition already in stockpile.

The delay in the government accepting the doctrine of credible minimum deterrence, the delay in appointing a strategic forces commander, a national command authority and executive committee, the widely prevalent image of a slow nuclear arsenal build-up, the delays in Agni missile testing and various other indicators which are available to professionals, all have convinced the US and others that the build-up of the Indian nuclear arsenal has been on an extremely responsible and deliberate pace under the NDA government and later.

Therefore, the criticism of the Indo-US nuclear deal by the former NDA leadership, especially about the capping of our nuclear arsenal, is a case of sour grapes and is not meant to be taken seriously.