BEFORE THE RUSSIANS took over Afghanistan, this country was putting pressure on both India and Pakistan to thwart their making any further progress on the development of nuclear weapons. Nothing in the past months has suggested that the region would be improved by these countries' acquiring nuclear arsenals. The incendiary politics of the region and the fragility of many of its governments underline the point. Then why should American nuclear non-proliferation policy even be an issue now? Because certain aspects of the crisis in the Persian Gulf region and South Asia have made it so: Reminders of the vulnerability of the oil supply have encouraged those who would like to proceed with nuclear energy technology with a minimum of precautions against the misuse of that technology for bomb-making purposes. And pressures being brought on both the Indians and the Pakistanis to forgo nuclear explosives are thought likely to interfere with the new post-Afghanistan need to work with these countries to bolster the region's defense.

At the time of the Russian invasion, the United States was facing a March 1980 deadline, set by law, when India would have to accept international safeguards on all its nuclear facilities or face a halt of U.S. nuclear cooperation. Two years of persistent efforts to reach agreement on this point had failed, leaving two equally unattractive options for U.S. diplomacy: cut off nuclear supplies (which would end all hope of eventually securing Indian cooperation and raise the likelihood that India would seize and reprocess U.S.-supplied spent fuel already in that country) or waive the law -- without reason to expect a future change in Indian policy (which would preserve a semblance of good relations with India, but damage the credibility of U.S. non-proliferation policy elsewhere, especially in Pakistan).

In Pakistan, the major thrust of U.S. policy was a continuing -- and so far futile -- search for a combination of incentives and threatened sanctions powerful enough to persuade the government of Gen. Zia ul-Haq to halt its clandestine nuclear weapons program.

Since the invasion of Afghanistan, the administration has announced that it will seek a waiver of the law that prohibits assistance to Pakistan because of its nuclear weapons work, and is apparently considering the sale to Pakistan of A7 long-range fighters -- planes appropriate for use against India. To assuage the Indian reaction, the United States has already agreed to sell essential -- and previously denied -- sophisticated electronic equipment for India's long-range fighter planes (primarily planned for use against Pakistan) and is reported to be planning to continue nuclear fuel shipments after the March deadline.

This balancing act -- the attempt to preserve cordial relations with both India and Pakistan while letting nuclear developments take a back seat for the time being -- is unlikely to work. A more promising approach would involve an all-out effort to halt Pakistan's nuclear program, using the leverage acquired through military and economic assistance. This effort would almost certainly be doomed by a U.S. decision to continue nuclear supply to India beyond the March deadline, for in Pakistani eyes the West's non-proliferation policy is already flagrantly discriminatory: India, after all, exploded a nuclear bomb without any penalty. A U.S. decision to stick with the statutory deadline would have the added benefit of showing others around the world that we are serious about non-proliferation.

This country should also try to get China to help. In addition to its undisputed influence with Pakistan, the People's Republic has a compelling national security interest in not having two nuclear neighbors -- the Soviet Union and India -- and its differences with India are, at least by comparison with others in the region, minor. Improved Sino-Indian relations could do much to moderate Indian policy and improve the prospects for a non-nuclear South Asia.

The administration has apparently decided that the immediate Soviet threat in South Asia poses a greater peril to world peace than the longer term possibility of a nuclear arms race between India and Pakistan, with China and the Soviet Union as substitute players on opposing sides.At best, that is a questionable decision, especially when it is possible to deal with both threats at once.