The Test before Jimmy Carter in his State of the Union address was to make some sense of the chaos that has overwhelmed both international life and his own former foreign policy. He did that pretty well. With the right focus, the president moved forward his effort to cope with the now generally perceived threat the Soviet Union poses to "the free movement of Middle East oil." This he did by a declaration that "an attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America, and such an assault will be repelled by any means necessary, including military force."

Others can argue whether this rates as a "Carter Doctrine." Certainly it is a historic and structural change, one whose implications will be long in unfolding, when a president explicitly bestows on a whole additional region a strategic value worth the United States' going to war to protect. Many questions remain: What is the extent of the "Persian Gulf region"? Are all parts of it equal? What constitutes "an attempt" to gain control? What does "gain control" mean? Will further programs be required beyond those already set in train by President Carter? What sort of cooperation is expected from ther nations in the region -- and from other nations dependent on the oil? How will the United States react if such cooperation lags? These diplomatic and military blanks remain to be filled in by further policy decisions and by the passage of time. But a reasonable and necessary framework now exists in which they can be filled.

The point of the exercise is not merely to prevent further Soviet inroads. It is to prevent further Soviet miscalculations.Moscow's Afghan operation appears to have been just such a miscalculation, brought on at least in part by a Kremlin estimate that the United States would not react strongly and followed by the general gearing up that the president outlined Wednesday. Another such miscalculation could produce war.

No one should expect, however, that mere words will convince the Kremlin, any more than they satisfy many of Mr. Carter's domestic critics. In recent days, the president has announced various steps (a search for bases, new deployments, his defense budget plans, the grain embargo, the Olypic boycott and aid to Pakistan among them) intended to convey that the United States now means business. Wednesday he called for an even more meaningful step -- revival of draft registration, which like the draft itself, was a casualty of the Vietnam War.

Only a few months ago Congress resoundingly decided against reviving registration: the case for not experimenting further with an all-volunteer force had not been convincingly made, and few legislators wished to brave the widespread popular resistance to anything smacking of a return to involuntary military service. The question now is whether new international conditions make it prudent to anticipate military-manpower needs that only a revived draft could fill, and whether, such needs aside, registration and perhaps the draft itself should be revived to send a signal of popular resovle -- and to avoid the contrary signal that a defeat of the president's proposal would now signify. We intend to return to this issue. Meanwhile, we note that, given its special emotional and participatory nature, the debate on it may be the closest thing to a national referendum on the president's new policy that the country is likely to see.

And debate there should be. The country is moving into an extended crisis in which national policy can be no more effective than the extent of informed public support achieved for it. The registration-draft issue is just one aspect of the debate, though a particularly valuable one: it makes the country facethe true costs of engagement in the Persian Gulf in precisely the way that Lyndon Johnson, to his and the country's ultimate dismay, never faced the country with the true costs of the Vietnam War.

The war issue must be another aspect of the debate. The War Powers Act confirmed the wise principle that a decision to go to war must reflect the "collective judgment" of the executive and Congress. Congressional scrutiny of Mr. Carter's new warning to defend American interest with force can help remove any element of rashness and can add an element of gravity and credibility to his stated intentions.