THE UNITED STATES has stopped filling its Strategic Petroleum Reserve -- an astonishing acknowledgment of national indecision and vulnerability. The reason is apparently a threat that, if this country continued to build its oil reserve, Saudi Arabia would respond by cutting its production. The Saudis are prepared, for the present, to keep production high as long as Americans consume it as they go. But if the United States stores some of that oil, as insurance against future disruptions, the Saudis hint they will sell less and bring back last spring's shortages. How is the country to extricate itself from this dangerously weak position?

Denouncing the Saudis is no solution. The Saudis can point out, correctly, that they are already running certain risks to help the United States and its industiral allies. The Saudis live in a turbulent part of the world. The Iranian revolution, across the Persian Gulf, is by no means over. The Palestinian movement generates guerrilla organizations for which the oil sheiks are obvious targets. The radicals of the Arab world keep pressing the Saudis to cut production sharply, in order to force prices still higher and to compel drastic political concessions in the peace negotiations between Israel and its neighbors.

The Saudis can argue that they have not caved in to those pressures but, on the contrary, they increased exports substantially last July. Yesterday they announced that they will continue exporting at that level through the end of the year. But they do not care to increase their political risks among their neighbors by letting Americans use that oil to build up their strategic stockpiles.

From the American perspective, the timing of this episode is instructive. A year ago the United States was filling the strategic reserves at a rate of more than 200,000 barrels a day, much of it Arab oil, with no objections from anyone. But by August, it was down to 50,000 barrels a day, all of it Mexican. Since the beginning of this month, the storage rate has been zero. What has shifted power so sharply toward the Saudis, and away from Washington? The fall of the shah and the fall in Iranian imports have made the Saudis more important than ever to the countries that run on imported oil. But when a shortage hit the United States last spring, and caused gasoline lines, the public reaction was frantic and vehement. It left a widespread impression abroad that the American political structure can't take the strain of even a limited shortage of gasoline.

If Americans let the rest of the world think they are desparate for more oil, they ought not to be surprised when other governments try to exploit that craving. But if Americans don't like the price they must pay to get more foreign oil, the answer is to take less of it -- beginning not in some future decade, but right now.