THE 1980s HAVE BEGUN with the brutal Soviet invasion of Afghanistan, the collapse of detente and the distinct possibility of direct U.S.-Soviet confrontation in the coming weeks in Pakistan or Iran. The world seems closer to a major war than at any time since the 1930s. The informal, de facto rules of the Cold War have broken down.

For a generation, the United States conducted military interventions in Iran, Guatemala, Lebanon, the Dominican Republic, Vietnam, Cambodia and elsewhere. The Soviets invaded Hungary and Czechoslovakia, but outside the area occupied at the end of World War II by the Red Army Soviet military expansionism was contained. The United States was free to dispatch its forces around the world outside the Soviet bloc without courting a risk of nuclear war; the Soviet Union, as the Cuban missile crisis showed, was not. In the past five years, however, Cuban troops backed by the Soviet Union intervened in Angola and Ethiopia, without American response.

This operational code of the Cold War was based on shared perceptions of power. With the invasion of Afghanistan, the Soviets have demonstrated that the old rules no longer apply. Their willingness to send their military forces outside the Soviet bloc and to brook the predictable consquences is particularly disturbing because it lends credence to the fear that old Russian imperial ambitions in the whole strategic area have been revived.

Henry Kissinger's structure of peace, fragile as it was, is collapsing. The fundamental question now facing the United States is what can take its place.

The urge to "punish" the Soviet Union for naked aggression is understandable, and the impulse to do it with symbolic military measures is predictable. But the military responses now being planned show a basic lack of understanding of the dimensions of the present crisis and a failure to take a hard look at the consequences of planned military moves.

There is rapidly developing in this country a political myth in the tradition of the "Yalta sellout" and "Who lost China?" slogans of the 1940s, a myth that holds that military weakness is behind our current predicament. Yet, the United States does not lack the airborne divisions, planes and ships to launch a military operation against Iran right now. And even tripling such forces cannot rescue the hostages.

In Vietnam the mismatch between military power and the political problem we were seeking to solve was the heart of the tragedy. Now we appear ready to bring back the Green Berets in modern dress, another military fix. Once again we will assign to the armed forces impossible missions, and once again the prestige and power of the United States will suffer. But this time the war is already regional and threatens to involve more than a billion people.

The military options are all unpromising. The instability of the region is casuing the U.S. to resort to the very policies that have promoted the instability.

We forget that the shah fell not because he lacked arms -- we sold and gave him $20 billion worth -- but because he was a corrupt, brutal and hated ruler. The arms served to catalyze public discontent and to symbolize U.S. responsibility for maintaining his tyranny.

In the same way, arming a brutal, unpopular government in Pakistan will strain the fragile bonds that keep that collection of nationalities together and will exacerbate the separatist movement of the Baluchis and Pashtoonis, all of which plays into the Russians' hands. Arming Afghan guerrillas or Pakistanis to fight in Afghanistan would be both cynical and foolish; the fighting might serve to keep the battle in the public eye but it could not liberate Afghanistan from the Soviet army. In the process a good many Pakistanis and Afghans would die and the Rusians could be provoked into a Cambodia -- style incursion against the rebel "sanctuaries." A revived India-Pakistan war is a likely consequence.

A Chinese "punitive" invasion of Indochina would no doubt distress the Russians, but the only lesson they would learn from it is that a general South Asian war was inevitable. Establishing U.S. bases in regimes as politically vulnerable as Sadat's Egypt or Saudi Arabia is crackpot realpolitik .

There is only one real military option to counter further Soviet aggression, and that is to keep raising the risk of nuclear war and to make it ever more "credible." By definition, that means basing national security policy on bluff, for there is nothing the Soviets could do in the Middle East that would be as destructive to the vital interests of the United States as a nuclear war. A nuclear strategy is an exercise in controlled recklessness. It is based on the expectation that the Soviets will back down in a confrontation or that the consequences of a nuclear war can be limited. Both are increasingly dubious propositions. In a world brimming with armaments, bluffs are likely to be called.

The most dangerous aspect of the reviving political myth of American weakness is the notion that it was a shift in the nuclear balance that emboldened the Russians to act in Afghanistan. The United States has the nuclear arsenal to destroy the Soviet Union utterly and the Soviets know it.

Far from looking weak militarily, the United States looked as if it had abandoned detente and was prepared to resume the quest for massive military superiority. SALT was already as good as dead. The United States had already announced a commitment to a major escalation of the military budget. The decision to emplace in Europe the cruise missile and Pershings, a new strategic nuclear weapons system as far as the Soviets were concerned, had been made and Brezhnev's October offer to negotiate a reduction in European-based nuclear weapons had been dismissed. The motives in Washington may have all been defensive, but they did not look defensive in Moscow. As they looked out from the Kremlin, Soviet leaders saw West Germany moving closer to acquisition of nuclear weapons and a U.S.-Chinese military alliance taking shape. The U.S. military programs of the 1980s would restore an overwhelming nuclear superiority to the United States unless matched at a fantastic cost.

The stakes are much too high to base policy on a view that the Soviets have fixed intentions. Whether the Soviet motivations were "offensive" or "defensive" matters less than whether it is possible to restore a structure of peace that can inhibit further military moves by the Soviet Union.

The great danger of the 1980s is that the possibilities for miscalculation have increased enormously. If President Carter appears a vacillating and uncertain leader, the Soviets appear mercurial and unpredictable. With President Brezhnev about to leave, it is not clear who is in charge. A "tough" policy is needed, but mindless military escalation is not the route. A policy that can impress friends and adversaries is one rooted in a clear view of vital interests, a realistic awareness of what can and cannot be achieved, and a steadiness of direction.

The ambiguity of policy and intentions in both capitals is creating a moment of extreme danger and, like the Cuban missile crisis, a time of opportunity as well. Because the old ground rules have broken down, de facto rules about what the superpowers can and cannot do must be put into place. The new rules will either be forged in the crucible of confrontation or they will be arrived at by explicit agreement.

If we are to slow down the drift to war, new principles governing superpower behavior must be negotiated. They should be simple and explicit.

For example, both superpowers could agree not to deploy their forces in any country in which they are not now located. Such a freeze on bases and troop deployments would outlaw future Vietnams, Dominican Republics, Czechoslovakias and Afghanistans. Proxy armies, as in Angola and Ethiopia, would be expressly prohibited. Such an agreement would clearly be in the U.S. interest since, unlike the first postwar generation, the Soviets now have more opportunities for military intervention than does the United States.

Why would the Soviets agree? No one knows for sure that they would. However, their record of military intervention has not been spectacularly successful. In Egypt, Sudan and Somalia, they lost control and made enemies of the countries on which they had lavished military aid. Pacifying Afghanistan will not be all that easy and the price already paid has been an overwhelming vote of condemnation by the Third World nations. The stated goal of their diplomacy has been to establish the principle of equality with the United States in military relations. Clear ground rules that inhibit both superpowers equally are in their interest as well as in ours. If there is a structure of peace that protects legitimate Soviet interests, then there is a good chance that they would renounce unilateral military and paramilitary action.

The United States should work for a neutralized Afghanistan, with borders guaranteed by all the states in the region and with Soviet troops withdrawn. The analogy would be Austria -- from which Soviet troops also withdrew -- militarily neutral but with an internal political system closer to that of the Soviet bloc. (Austria, of course, in economic and political terms is part of the West.) It would be foolish to underestimate the difficulties, but it is a realistic goal as part of a larger process for the restoration of a less dangerous U.S. -Soviet relationship.

Neither superpower can control internal political events in the Third World. An agreement that reflected such an understanding of our historical moment is absolutely crucial to the avoidance of war. The failure to grasp the power of liberation ideologies is the fundamental weak point of the official view in Washington, and, it seems, in Moscow, too.

In one sense we are at the "end of ideology." Neither "communism" nor "capitalism" reamins a credible philosophical system for organizing society in the contemporary world. There is growing suspicion of all ready-made systems. The existing models are too much beset by internal contradtions and failures. They mean too many things.

There is panic and violence in the world -- not, as at other historical moments, because of a fanatic belief that one system or another has a monopoly on truth, but because of widespread feelings that no one in charge knows what to do. The failure of both "socialist" and "capitalist" regimes to bring liberation or dignity to billions of people has unleashed a profound spiritual reaction -- a radical rejection of the dominant international culture.

The popular impulse is not so much to build a "nation" in the 19th century sense of the word as to restore a sense of cultural and religious autonomy and to achieve an identity which -- as in the case of the Kurds, for example -- may be transnational. But the transforming impact of popular passions is real, and in the corridors of power it is hopelessly misunderstood. The official American worldview ignored Islam in Iran until the mobs were in the streets. The Russians have been more aware of popular passion as a major political force of our time, but they too are so bound by the traditional geopolitical view of the world that their only response is to try to crush it.

Given the realities of world power and the parallel reflex responses in Washington and Moscow, there is no way out of the national security dilemma as it is now being defined. Unless we change the conceptual framework, we are doomed to a series of military moves and countermoves that cannot be kept under control. But the United States does have an historic opportunity to help build a new world consensus to contain aggression. It can do that only by identifying more with the concerns of the weak states where the world's majority lives.

To build a world consensus we need new ground rules that will be equally applicable to everybody. To curb proliferation, the U.S.-Soviet competition in nuclear weapons must come to a halt. To build a new world majority for reestablishing the minimum international order necessary to survive the rest of the century, the poor countries must have a significantly greater stake in that order.

The principal security problem for the United States in the 1980s is mounting instability everywhere; the Russians are just a part of the problem. Making new military alliances with weak, illegitimate governments creates more instability. The escalating disorder in the world requires a clearer relationship with the Soviets, not a breakoff in relations. We need more emphasis on human rights, not less; only legitimate governments, not repressive juntas, can keep order over the long run. We need accommodation with the developing countries on economic issues. We dare not let our obsession with the Soviet Union define our global security policy.

A few years ago these were the stated views of the Carter administration. Now that effort to develop rational security policies appropriate for the 1980s is being abandoned, and we march to catastrophe under the banner of an obsolete realpolitik. If we could learn that uncontrollable forces of liberation are on the move in the world and they they need not be our enemies, we could help to create a political climate in which aggression can be contained.