A treaty eliminating intermediate-range nuclear forces (INF) should not be approved unless the United States and the Soviet Union agree to a cap on their long-range, or strategic, arms, the chairman of the House Armed Services Committee said in a speech released yesterday for delivery today.

Rep. Les Aspin (D-Wis.) said the INF treaty, now in the final stages of negotiation, would not "make sense" unless both superpowers agreed first to abide by limitations established by the unratified 1979 SALT II treaty and strategic arms reductions of up to 50 percent that U.S. and Soviet negotiators are currently discussing.

Otherwise, Aspin said in a speech prepared for delivery to an arms control symposium in Crystal City, the Soviets "can easily and legally circumvent the INF deal" by aiming extra strategic weapons at European cities and military facilities now targeted by the INF missiles.

Because only the Senate ratifies treaties, Aspin will not have a vote if the United States and the Soviet Union reach an INF accord. But he is expected to influence congressional debate.

Aspin said he believes the prospective treaty is "far from ideal . . . but close to a political reality." Raising a number of concerns about its impact on relations between the United States and Western Europe, he said, "If I were to pick the single most important reservation to be attached to the ratification of the INF treaty, it would be that this treaty should not be implemented unless SALT II is adhered to."

President Reagan abandoned the SALT II arms limitations last year in response to alleged Soviet treaty violations, after informally abiding by them for six years. In response, the Soviet Union has said it is not bound by the limitations.

Since then, the administration has strongly resisted legislative attempts to reinstate the limits.

Senior State Department arms control adviser Paul H. Nitze told the symposium yesterday that European targets covered by existing INF weapons could indeed be hit by excess strategic arms. But he emphasized the administration's position that the problem can be solved by negotiating the 50 percent reductions.