THE LATEST COUP in Kabul adds to the sense that events across the whole critical region spanning the Persian Gulf are swirling out of control, or out of friendly control. It is, to put it mildly, a disturbing spectacle, and the more so for the fresh precedent of massive open Soviet military intervention added to the region's already dangerously high level of internal volatility -- and this at a moment of extraordinary tension on account of the brutal embassy seizure in Iran. Only a very cynical Soviet leadership, with the resources to make its cynicism operative, could have contemplated such a move. Undeniably, its effect is to intensify the pressures on Jimmy Carter to . . .

Well, to what? It has become almost routine for people to complete the thought by saying: to respond, to wake up, to rearm, to accept that politics is not a garden party, to let friends and enemies know we mean business, to get tough. Point one: some part of this prescription is surely correct. Taking the political long view (over the shoulder, retrospectively) you could argue that this is cruel because it is not what Jimmy Carter was elected to do, and fate has played him foul: he was elected to comsummate the country's post-Vietnam transition to what he and his supporters (a majority, remember) felt was an essentially fair-minded and eminently rational world, one in which persuasion would be the chief element leading otherwise disparate or hostile nations to reconcile their aims. The Soviets, the mullahs and countless others have seemed determined to disabuse him and his loyal constituency of this sunny view, and Mr. Carter has, in consequence, done, or started to do, much of what he has had to in the way of preparing broader military options. Wisely, he has not acted impetuously or carelessly in Iran. But the defense budget is going up, new missiles are moving ahead, new bases being sought, and so forth.

Still, this does not satisfy the growing unease expressed about the government's seemingly passive, long-suffering response to the dangerous turmoil and acts of aggression committed in Iran and Afghanistan. That has to do, not with announced military plans, but rather with the question constantly being agitated of the quality of Mr. Carter's leadership. It is not so much that he is letting the nation's defenses slip, or that his crisis-management skills are not up to snuff. It is that he has not yet found the right voice in which to speak to the American people about the perils they face in the world -- and to the world in the name of the (currently outraged) American people. There is in his tone and his message an apparent absence of urgency, a surfeit of let-us-be-patient, day-at-a-time resignation. No -- we can hear the response now -- we are not recommending a lot of chest thumping, hollering or posturing; and, yes, we do appreciate the dangers of setting off Islamabad-type mob scenes and providing a pretext for political retaliation and upheavals that ultimately hurt our interests, not to mention the danger of killing the hostages.

Nevertheless, it seems to us that the time has come for Mr. Carter to convey to both the public at home and the world overseas what one keeps hearing around Washington -- that Jimmy Carter is damned mad and ready to settle some scores and increasingly less sentimental about some of our allies and nonaligned clients, not to say our great partner in detente, the Soviet Union. And it is surely time to convey to those whom we hold responsible for the ordeal in Tehran that we are not bottomless reservoirs of logic and understanding, but that we are going to tighten the pressures we can bring until their effect is clearly felt and that we are not going to take till Easter to do so.

If the stories from behind the scenes are true, doing this should not require that the president adopt some alien, artificial style. It would evidently require only that the president contrive to share with the public and with the nations and parties involved in our current torment the mood of anger and determination he feels himself. Restraint is fine, so long as it is restraint of something, restraint of an excessive act -- as distinct from merely not feeling up to doing anything and calling that "restraint." Mr. Carter is not in danger of reacting with excessive violence, and we don't wish he were. But he is in danger of seeming almost reticent in his tone and approach to the events that have come to consume his energy and attention. If he is really feeling mean, and we hope he is, he needs to show it in the pressures he brings on the Ayatollah & Co. and in his public appearances, acts and speech.