The massive Soviet military occupation of Afghanistan has provoked an unambiguous American pledge of support for Pakistan in the event of Soviet aggression, accompanied by an urgent reconsideration of U.S. military aid. This was a necessary response to the arrogant display of Soviet power symbolized by the direct interevention of Soviet forces in the Kabul coup last week. Before rushing into specific military aid commitments to Islamabad, however, the United States should identify accurately both the nature of the challenge posed by Soviet control of Afghanistan and the conditions under which aid to Pakistan would be effective.

American military aid should not, in my view, be primarily addressed to the hypothetical scenario of a Soviet frontal assault on Pakistan comparable to the present invasion of Afghanistan. Rather, the United States should focus on the more credible possibility that Kabul will seek to encourage the festering separatist movements in the adjacent Baluch and Pushtun border regions of Pakistan and Iran.

Selective military assistance designed specifically for counterinsurgency purposes and for a limited border "tripwire" role would be helpful to Pakistan in dealing with this type of Soviet challenge -- but only if Islamabad is willing to take the accompanying political and economic measures required to defuse separatist appeals.

Pakistan has been dominated since its inception by its majority linguistic group, the Punjabis, who constitute 58 percent of the population. This Punjabi predominance is bitterly resented by the other three groups that make up the country, the Baluch, the Pushtuns and the Sindhis, whose ancestral homelands cover 72 percent of Pakistani territory.

All three of these groups contend with varying degrees of justice that they are excluded from their fair share of political and economic power by a Punjabi-controlled military and bureaucratic autocracy. Increasingly, influential leaders among all three groups have been thinking in terms of secession from Pakistan and have been exploring the possiblities for winning their independence with foreign help, whether from the Soviet Union, the Arab world, India or the West.

Separatist sentiment is strongest in the strategically located Baluch area, which has a 750-mile coastline stretching along the Arabian Sea across western Pakistan and eastern Iran directly to the south of Afghanistan. Baluch nationalist factions have long dreamed of a "Greater Baluchistan" that would unite the five million Baluch in Pakistan and Iran. Should an independent Baluchistan come into existence under Soviet auspices, Moscow would have ready naval access to the Persian Gulf and would gain a new position of leverage along Iran's eastern flank.

In the case of the Pushtuns, separatist feeling is rooted in the fact that the Pushtun population of 14 million is presently divided almost equally between Pakistan and contiguous areas of Afghanistan. Pushtun dynasties in Kabul ruled a united Pushtun kingdom, encompassing most of what is now northern Pakistan, until the British Raj pushed back the Afghan boundary to the Khyber Pass little more than a century ago. More recently, Kabul, encouraged by Moscow, has periodically promoted a movement for an Afghan-controlled "Pushtunistan" to be carved out of Pakistani Pushtum areas. This movement has been eclipsed by the Afghan civil war, but it could well be revived if the Soviet-backed Babrak Karmal regime stabilizes its military and political position.

Confronted by the specter of a possible Soviet push southward toward the Arabian Sea, the United States clearly has an interest in promoting a more stable Pakistan capable of resisting separatist pressures. But the U.S. delemma is that the Punjabi-dominated Zia Ul-Haq regime has so far failed to take even a modicum of the political and economic steps needed to neutralize separatist sentiment in the Baluch and Pushtun areas and thus to facilitate their effective military defense if this should become necessary. Many of the established political leaders in these areas are still prepared for an accommodation with Islamabad and could do much to counter the separatist offensive if they could show progress in winning greater justice for their people. The essential precondition for significant inputs of American military aid to Pakistan should, therefore, be an interim political settlement between the central government and Baluch and Pushtun moderates providing for a wide degree of regional autonomy, a major increase in locally controlled development expenditures and representation in military decision-making affecting their areas.

Given a meaningful devolution of power and resources, Islamabad would have powerful local allies in the Baluch and Pushtun regions, whose cooperation would be essential in mobilizing any effective tribal cooperation with the Pakistani military in anticipation of Soviet-supported separatist adventures. In the absence of a political settlement, there is a great danger that U.S. weaponry would be used not against Soviet-supported subversion but against Baluch and Pushtun dissident groups fighting for their legitimate rights as Pakistanis.

This is precisely what happened when tensions between Islamabad and a non-communist Baluch provincial regime exploded in a savage and inclusive guerrilla war from 1973 to 1977. The Pakistani Air Force used U.S.-supplied Iranian helicopters to raze Baluch villages indiscriminately, leaving a legacy of hatred that has merely intensified separatist feeling.

It should be emphasized that a limited U.S. aid program addressed to Soviet-supported separatist moves would not be intended to give Pakistan the capability for defense against direct Soviet intervention, which could be effectively stopped only if the United States and other powers were to intervene with their own forces. A misconceived, oversized military aid package would not only fly in the face of congressional restrictions, but would also have self-defeating consequences.

Domestically, it would strengthen the already disproportionate power enjoyed by the military in Pakistan, Internationally, it would needlessly arouse Indian fears that Islamabad is seeking to use the Afghan crisis to boister its power position vis-a-vis New Delhi. In seeking to shore up Islamabad, the United States should consult closely with Indian leaders, recognizing that India is the preeminent power in South Asia and that a breach between New Delhi and Washington over the issue of U.S. aid to Pakistan would only play into the hands of Moscow.