THE UNITED STATES has a new position on limiting strategic nuclear weapons, and Cyrus Vance will be explaining it to the Russians in Moscow this week. At the moment, only its general outlines are known to the public. But enough has been revealed to indicate several things about the position the Carter administration has hammered out. It is bold; it is tough; it is sensible; and it points in the right direction.

Mr. Carter offers the Russians a choice: the relatively high levels of balanced armaments suggested in the Vladivostok agreements or genuine and substantial cuts. The first of these alternatives would "defer" the question of our cruise missiles and the Soviet Backfire bomber, meaning that a U.S. weapons system the Russians are keenly interested in curbing would be outside the realm of restraints. The second, under which the cruise missiles would presumably be limited, would also address the Soviet buildup of super-size ICBMs. Our cruise missiles and their growing arsenal of giant ICBMs would be continued and even, in some degree, "tamed." Both sides would be foregoing a measure of advantage for a larger measure of stability; both would be giving up something and also getting something.

Naturally, to get from here to there an enormous amount of complicated negotiating would be necessary. Mr. Carter has, in effect, "leapfrogged" the intermediate position, which many felt was disadvantageous to the U.S. and which left the high Vladivostok ceilings on numbers of arms intact while introducing strict curbs on American cruise missile development. And because the kind of agreement he would prefer is so bold, it will presumably require even more bargaining patience and ingenuity than have been needed in the past.

We note in this connection two facts. One is that you can already hear the first complaints that Mr. Carter has taken too tough a stand; that he is offering the Russians something they don't like and so is either a) not serious about wanting an arms deal, or b) just trying to nail down an American advantage. We think neither is true and that the administration's proposal, as we understand it, goes directly to the most destabilizing and frightening aspects of the arms competition. That the Soviets have been indicating displeasure with it is neither surprising nor particularly conclusive as a guide to what they will ultimately do.

The other fact we note is that the 1972 accord with the Russians on offensive weapons runs out this fall. We think Mr. Carter has positioned the country well for meeting that deadline. There are choices: a quickly negotiated second step agreement along Vladivostok lines, which would leave the cruise missile and Backfore bomber out; a lapse of the agreement if all progress toward a new accord fails; or an extension of the agreement for a given period of time to complete negotiation of a genuine cutback to lower (balanced) levels of offensive strategic weapons. The last of these would clearly be Mr. Carter's choice. It is certainly ours. And we think it is worth the administration's working hard for.