The uncertain results of Zbigniew Brzezinski's trip to Islamabad provide an opportunity to think more seriously about the future of U.S. security relations with Pakistan. What sort of commitment is desirable? How much aid should be provided? Should U.S. combat forces be stationed there? These are tough questions, with no easy answers. In such situations, the American proclivity is to compromise -- to seek the middle ground. In the case of Pakistan, however, the middle ground is likely to yield the costs of close relations, but few of the benefits.

Before Christmas, the question of aid to Pakistan was not seriously debated. With a human rights record bad enough to make an Argentine general blush, a determined program to develop nucler weapons and shadowy ties with Libya's Muammar Qaddafi, the government of Gen. Zia ul-Haq posed stark challenges to a number of high-priority Carter administration initiatives.

Traditional factors also argued for avoiding too close an association with Zia. Moving closer to Pakistan has always meant that it would be more difficult to improve relations with India -- a larger, more stable, democratic nation. Beset by separatist ethnic movements, plagued by a deteriorating economy, lacking a political base of any substance outside the army, Zia's prospects for remaining in office have never been good.

Moreover, despite these weaknesses, Zia has been unwilling to compromise and has even demonstrated a streak of anti-Americanism. Its latest expression, his crude public dismissal of the recent U.S. aid offer, is only symptomatic. The coincidence, in November, of simultaneous attacks on the U.S. Embassy in Islamabad and U.S. facilities in two other Pakistani cities, to say nothing of the government's delay in rescuing the besieged embassy staff, raise more serious questions.

For all these reasons, the Carter administration remained cool to Pakistan until Soviet occupation of Afghanistan caused a sharp reappraisal. After all, Pakistan is the one nation in South Asia with a tradition as an American ally. It is a nation with which we already have a security commitment of sorts, expressed in an executive agreement signed in 1959.

Most important, Pakistan is situated geographically in a most fortunate spot, providing a potential support base for Afghani rebels, possible sites for air bases and naval facilities to support the Carter commitment to defend the Persian Gulf and potential locations for the types of technical intelligence facilities previously situated in Iran. Symbolically, a change in policy toward Pakistan would demonstrate to the Saudis, the Chinese and other nations the seriousness of the new resolve articulated by the president in his State of the Union message.

So far, however, the administration has not been prepared to go the full route. It has reaffirmed, publicly and privately, the 1959 executive agreement, but seems to ignore Pakistani protestations that the specific commitments it contains are ambiguous. It has announced its intention to seek relief from the legislation that prohibits economic and military assistance to nations that are developing nuclear weapons, but indicates an unwillingness either to make available sufficient economic aid to solve Pakistan's financial problems or to sell the types of military equipment the Pakistanis previously had requested.

The results of such halfway measures are likely to be the worst of two worlds: on the one hand, we have associated ourselves more closely with Zia regime, thus giving us a stake in preserving his government and foreclosing even the theoretical possibility of U.S.-Indian rapprochement. More significantly, we have sent an unfortunate signal to Pakistan and other potential proliferators as to the relative priorities we accord to the dangers of nuclear proliferation and the dangers of Soviet aggrandizement.

On the other hand, neither the U.S. commitment nor the military capabilities to be made available to Pakistan may be strong enough to deter new Soviet adventures in the region -- in response, say, to attacks on Soviet forces in Afghanistan -- or to reassure other interested nations of our new-found will and power.

One alternative would be a permanent and formal secuity relationship with Pakistan. This would involve the negotiation of an unambiguous mutual defense treaty, which would have to be debated and approved by two-thirds of the U.S. Senate. (The treaty could be worded so as to avoid any implications of U.S. complicity in threats against India.) There could be no firmer demonstration of American resolve to resist further Soviet encroachment in South Asia than a deliberate and public decision by the Senate, having considered all the problems previously mentioned, to commit the United States to the defense of Pakistan.

If such a treaty were approved, tactical air squadrons could be stationed in Pakistan, and other military facilities acquired, to ensure a prompt response in any military contigency. Unlike an executive agreement, a treaty would have the added symbolic benefit of expressing a commitment between nations, not between governments. And, finally, the acceptance of an unambiguous commitment would perhaps strengthen U.S. leverage in seeking to curtail the Pakistani nuclear weapons program. The most important successes in this area have come with those nations with which we have had the most intimate security relations.

Alternatively, in view of the many disadvantages of a close Pakistani connection, an effective policy might also be fashioned on the basis of a decision to avoid tying U.S. prestige to the future of Pakistan (and Zia). In effect, such a policy would seek to build a solid U.S. position in the region over the longer term, accepting -- for the time being -- some risk of further losses.

In such a case, however, it would be preferable to avoid the half-steps now envisioned. American interests are not well served by commitments that are not meant sincerely and cannot be supported; nor by military assistance that is too small for a real defense, but large enough to antagonize local rivals; nor by measures that indicate that high priority previously accorded to stemming proliferation was only of passing interest.

The Soviet occupation of Afghanistan has led to a sharp swing in the public's view of security policy. Neither moral outrage nor the tough rhetoric now so popular, however, provides the basis for effective policy. We need a full congressional review of the implications of our new posture, and conscious decisions to go ahead or not. If we face up to the full price of the new policies from the beginning, it may help us avoid the long term dangers of piecemeal commitments.