"The old man doesn't know what he is talking about." Time and again one hears that contemptuous refrain from Indians discussing Prime Minster Morarji Desai's refusal to develop nuclear explosives. It is another sign that the anti-nuclear barricades are eroding in South Asia.

The United States has mounted new efforts to discourage Pakistan from acquiring a production base for nuclear weapons, but India remains the key to the entire situation. Only if New Delhi exercises restraint can one imagine persuading the Pakistans to do likewise.

My own recent discussions and those of others in New Delhi make clear that Indian restraint is by no means assured. Desai has declared frequently that his government will not respect the provocative act of its predecessor in detonating a nuclear explosives, allegedly for peaceful purposes.He emphasizes, however, that he cannot commit his successors to this policy. While no one is certian who will take over after Desai, a number of possible candidates are known to differ with Desai's inclinations. Foreign Minster Atal Vajpayee, for example, frequently points out that his faction has always favored building the bomb.

Many intellectuals and journalists, as well as officials and technocrats, do not hide their condescension toward Desai, especially when it comes to his suspension of work on nuclear explosives. There is no evidence that Desai's remshackle coalition embodies a durable consensus for abondoning the nuclear course pursued under Indira Gandhi. What we are witnessing seems to be more a pause than a basic shift in India's technological evolution.

Somewhat surprisingly, reports of Pakistan's movement toward a capability for processing nuclear-weapons material are received rather calmly in the Indian nuclear group. One reason for this is the widespread view that the Pakistan's are too disorganized to succeed in a weapons program, an appraisal that contracts sharply with the vast-and warranted-self-confidence of Indian experts. But their contempt for Pakistan's capabilites may well dissolve into alarm in the coming months.

The endless disputations about Indain's nuclear future have one point of agreement: China is the problem. Both as the major competitor for regional influence and the principal threat perceived by Indians, the People's Republic weighs most heavily on New Delhi's defense Veitnam for its invasion of Cambodia reminded Indians of the rather casual attitude Peking has sometimes taken toward other countries' borders, including India's. Vietnam's "lesson" began with Vajpayee was in China, a coincidence that increased Indian anxieties.

The latest commontions in Indochina also amplified. New Delhi's concern about U.S. disregard for India's security problems vis-a-vis China. Coming so soon after normalixation of relations between Washington of relations between Washington and Peking, the left many Indians with the impression that America condoned China's presumption of dominance on the Asian continent. Seeing the link between normalization and great power polictics, Indians were offended and worried that they were neither considered nor consulted. The fact that New Delhi has long maintained diplomatic ties with Peking did not prevent it from thinking its security might suffer from Sino-American rapprochement.

This concern has a specifically nuclear dimension. Indian authorities and commentators have been irate that the United States, while demanding that India accept full international safeguards over its nuclear facilites, raised no objections to plans for nuclear cooperation between France and China. From the Indian standpoint, Washington would do better to resist improvements in the Chinese nuclear capability, which has been devoted almost entirely to weapons, than to lean on an india that has stressed peaceful nuclear efforts. This fury mounts further whenever there are hints of Western military cooperation with China-for example, the prospective sale of British jets to Peking. Reflecting a common attitude, one senior figure says, "We Indians recall Kissinger's asking how you could ignore a country with 800 million people that had the bomb, and we wonder whether the same thing would not to be true of a country that has 650 million people-and the bomb."

Ironically, the most vital voice for nuclear restraint may be that of the Indian military establishment. Though some officers are undoubtedly interested in the nuclear option, the prevailing military priority is modernization of conventional forces.

Arrayed against this prudent military judgment is the opinion of those strategists and technoligists who berate Desai for yeilding to President Carter's anti-proliferation pressure. They often couple this charge with jarring critiques of what one terms "that banal generalization called Gandhism," denying that India's espousal of non-violence has any bearing on the decision to seek nuclear weapons.

So determined are some members of Indian's technocracy that they would probably welcome a breach in nuclear cooperation with America. Their hostility is now focused on whether the United States will filfill its contracts to supply uranium for certain Indian reactors, if New Delhi rejects the safeguards Congress demanded in last year's Nuclear Non-Proliferation Act. Should this simmering confrontion lead the United States to cut off aid, proponents of the bomb are likely to gain the upper hand in New Delhi. Forced to go it alone, albeit more slowly that with American assistance, the Indian nuclear establishment could claim a larger relative share of national resources. Its elite members also expect to have greater influence over Indian security policy and, freed from insistent pressure for safeguards, could explore any technology they wish.

Obviously, it makes no sense to apply U.S. non-proliferation policy so inflexibly that the real effect is to strengthen its opponents. Both Congress and the president should know that this prospect is now impending in India. The United States will need creative diplomacy to avoid a thoroughly self-defeating outcome. CAPTION: Illustration, no caption, By Zarko Karabatic for The Washington Post