Pressure

In the lexicon of foreign affairs, some words are repeated with simplistic regularity until they become broadly accepted, without qualification, as an answer to problems.

One of these words is ''pressure.''

Currently, the word is applied with dogged repetition to relations between the United States and two countries: Israel and South Africa.

''If the administration would only put pressure on Israel, that nation would withdraw its forces from Lebanon and its authority from the West Bank and Gaza.''

''US pressure on South Africa would force that country to give up Namibia and alter its apartheid system.''

In each case, those who advocate pressure often have in mind dramatic actions on the part of the United States: the suspension of all aid to Israel, the cutting of diplomatic ties, and the withdrawal of all US investments from South Africa.

Calls for ''pressure'' are born of the strong feelings that exist toward the actions of both countries and out of the frustrations of many with the slower methods of diplomatic intercourse: the protracted diplomatic efforts in the Middle East and the complicated discussions about Namibia.

Calls for such pressure are based on a highly questionable assumption: that within the political structure of each of these countries concern over actions by the US out-weighs concerns over positions of individual political leaders, national pride, and national interests as defined by those in control in each country.

The US has itself demonstrated on several occasions how a proud nation reacts to dramatic outside pressure. The Arab oil embargo of 1973, as an example, led not to a basic change in America's Middle East policy but to a determined energy conservation that exists to this day.

To state that proud nations resist dramatic pressure, however, is not to rule out the influence of external acts and signals as instruments of diplomacy - under certain conditions. Such acts can include, at the proper time, suspension of aid, economic restrictions, or diplomatic distance.

Such external pressure, if applied at all, must follow the creation of widely supported demands for changes in policy within a country. Such demands must be tied to the existence of a broadly acceptable and reasonable alternative that will be seen by a substantial number in a country as satisfying the needs of security and national interests. External pressure applied without such conditions can reduce the chances that the necessary internal debate will ever materialize.

The pressure for a defined alternative must also have broad support within the US and be applied with steadiness. Opponents of change will look for signals from Washington that the US is either divided or not serious. Delays in actions ''for technical reasons'' that are quickly rescinded without achieving results undermine the credibility of any pressure.

Finally, such ''pressure'' on the part of the US must be tied to the final stages of a diplomatic effort, appealing to concerns that an opportunity may be lost, that time is running out, and that the nation may lose not only a chance for peace but its very basic relationship with the US.

In neither Israel nor South Africa have the conditions yet been created for this kind of effective external pressure.

In the Middle East the President's Sept. 1 proposal had within it the possibility of creating a genuine policy debate in Israel. That possibility has been eroded by the events in Lebanon and the absence, to date, of a persuasive response from the Arab side.

In South Africa the United Nations plan for Namibia held hope for an alternative. To an extent, the existence of that plan and the work of the ''contact group'' of five Western nations have resulted in South Africa's seeking, through direct talks with Angola, alternatives to that plan. A genuine internal debate among the white factions that rule South Africa has yet to begin on either approach.

In both cases, ''withdrawal'' is the issue: from Lebanon and the West Bank in the case of Israel; from Namibia in the case of South Africa. In neither case will the nations concerned withdraw without clear indications of the security arrangements that will follow. Pressures to ''withdraw'' that do not answer that question will only stiffen resistance.

The US role, in both cases, remains to continue the often frustrating, deliberate, and less dramatic diplomatic efforts in search of acceptable alternatives. When those have been established and there exists within each country strong sentiment for that course of action, at that point acts of pressure by the US might be a necessary and significant factor in resolving the isssues -- but not before.