PRESIDENT REAGAN deserves credit for the prospective INF agreement, whether one likes the accord or not. If he had listened to the voices from the State Department, he would never have proposed the zero-zero option to begin with, and would later have succumbed to the temptation to settle for a much worse bargain. If he had taken advice from the Defense Department, he would have backed off from his own proposal once the Soviets were inclined to accept it, thereby causing great political damage in Europe.

His negotiating stand over the last several years underlines a very basic lesson: The United States must stick to its positions and not negotiate with itself on behalf of the Soviets. As recently as 1984, congressional critics and some leading academics were predicting a dire crisis in U.S.-Soviet relations if this country proceeded with the Pershing II and ground-launched cruise missile deployments instead of making preemptive concessions. Reagan not only disdained their counsel but his Strategic Defense Initiative focused Kremlin minds on the Soviet's own need for arms control. He got the deal he wanted.

The full measure of Reagan's success is best illustrated by a short list of positions abandoned by the Soviets in the face of American toughness:

That the initial zero-zero proposal -- both sides eliminating their intermediate range nuclear forces (INF) -- was totally unacceptable.

That the deployment of American INF forces would end all arms-control negotiations.

That the agreement must cover British and French nuclear forces.

That the talks must include other intermediate-range U.S. nuclear delivery systems, such as forward-based bombers.

That any INF agreement must be tied to an agreement that eliminates the SDI.

That the Soviet Union could retain 100 intermediate-range missiles in Soviet Asia.

To be sure, the INF agreement is a limited agreement not to be portrayed as a fundamental breakthrough in U.S.-Soviet relations. Nonetheless, it does open up a new chapter in the intricate East-West relationship in Europe. In that new chapter, there are opportunities for an active, affirmative longer-range U.S. strategy.

Since everyone agrees that war in Europe is unthinkable, peaceful change becomes the only option for Europe's future. Peaceful change is seldom neat, precise or clearcut -- even as it generates hope, it can inspire fear and even paradoxical responses. Our policies are premised on the expectation of change -- on the notion that change is both desirable and inevitable. Yet the very discussion of such change quickly generates fear among western statesmen. Some leaders and commentators even adopt positions similar in substance to those of their communist counterparts -- any suggestion that political and security arrangements born in the 1940s and 1950s should be revised in the late 1980s and 1990s is denounced as destabilizing and even dangerous.

Yet the fact is that today Europe is stirring. The manifestations of peaceful change are increasingly evident at two levels.

First, in both halves of divided Europe, there is a growing political restlessness. In the heart of Europe, we can see the emergence of the notion of a Central Europe. Today, the average Czechoslovak, Hungarian or Pole openly admits he feels closer to the typical Austrian, German or, still further west, Frenchman than to his eastern neighbors.

Second, the leaders of the two superpowers are increasingly preoccupied with events outside of Europe. It is clear that resuscitating the Soviet economy will be Gorbachev's principal priority in the years ahead, while the unending war in Afghanistan, now almost eight years long, is becoming an increasingly painful distraction. At stake in Gorhachev's economic reform efforts is nothing less than the status of the Soviet Union as a first-rank power. Moscow is a superpower solely in the military dimension -- and it knows it. If Gorbachev cannot breathe life into the moribund Soviet economy, by the next century the USSR could lose its superpower status.

Potentially at stake in the Soviet-Afghan war is the internal cohesion of the Soviet Union. Already the war has reverberated in the nascent national self-assertion of the non-Russian nations of Central Asia, most evident in the nationalist riots in Alma-Ata in late 1986. If Gorbachev fails to resolve the war either militarily or politically, these Muslim peoples -- who have more in common with the Afghan freedom fighters than with their Russian imperial overlords -- will probably become ever-bolder in asserting their legitimate national rights. That must be a disquieting prospect for the Russian leaders of the world's last surviving multinational empire.

Meanwhile, American leaders will have to focus much of their attention on their southern periphery. Potentially at stake in Central America is America's capacity to project its power, and defend western interests, throughout the world. For the United States to maintain its global security commitments, including those in Europe, it must be free from the burden of mounting a defense of the continental United States. But if the Soviet-Cuban presence in Nicaragua destabilizes the entire region -- or especially if regional instability fuses with a deepening internal socio-economic crisis in Mexico -- the American public will be plunged into a state of isolationist anxiety, and the United States will inevitably pull back from its forward positions.

Thus, the incremental and evolutionary process of historical change -- both within Europe and within the two superpowers -- has begun to alter the geopolitical landscape of both halves of Europe. In the decades ahead this process could even accelerate.

It is not surprising that these gradual changes are inspiring fear within the Kremlin and prompting a defensive attitude on the part of the Muscovite empire; any change is detrimental to the rigid and cohesive structures which Moscow still seeks in the eastern bloc. But we, the pluralist west, should not share that attitude. Instead, our policies should seek to move this change in a constructive direction.

It is surely not wishful thinking to observe that a Europe which becomes gradually more independent is tantamount to the historical attrition of communism. In eastern Europe, communism is already finished as an ideology and as a motivating force. No one -- literally no one -- takes the ideas of communism seriously as a worldview or as a guide to action. I was struck on my recent trip to Hungary and Poland that the Soviet Union has lost even its ability to instill fear in peoples living on its frontier. While no one harbors any illusion about the clout of Soviet military forces, there is a growing feeling that the Soviet army will not be the ultimate determinant of east European history.

During that visit, I called upon a distinguished clergyman in eastern Poland. I wanted to talk about conditions in Poland, but another topic was very much on his mind: What will Russia look like after communism!

Even the leaders of eastern Europe and the Soviet Union know that in every significant respect they are falling behind the west. Average per-capita income in eastern Europe is roughly half that of the major west European countries. But even that comparison underestimates the impoverished state of eastern bloc consumers whose currencies have little purchasing power in terms of real goods and services. Moreover, there is an increasing disparity in rates of economic growth and productivity between East and West. Most important, in terms of high-tech competition, the East has yet to leave the starting gate. Even the Soviet Union has, on a per capita basis, only one fifteenth the number of industrial computers that major western countries have, and one forty-fifth the number in the United States.

None of that is lost on the peoples -- or even the leaders -- of eastern Europe. What we are seeing is the advanced stage of a process of organic rejection by east Europe of a system and ideology artifically transplanted to its countries after World War II. That system, based on an historical model derived from Russian experience, was altogether inimical to the psychology, culture and history of the east Europeans. As such, it has no historical staying power.

Just as significant, a corresponding process is beginning to appear in the Soviet Union itself: The Russian past is asserting itself over the Soviet present. Wait until next year! Soviet Russia will be celebrating the 1000th anniversary of the birth of Russian Orthodoxy. With Soviet communism increasingly moribund as an ideology, one can expect outbursts of Russian patriotic fervor and even strong demonstrations of renewed Russian Orthodox faith.

In this context, we must seek to encourage the process of change by creating a geostrategic environment in which it will flourish. The point of departure is for the west to make a systematic effort to mitigate the importance of the military dimension of the East-West conflict. In doing so, we must recognize one fundamental fact: The Soviet threat is still real. It is not an accident, after all, that the Warsaw Pact holds all of its exercises in an offensive mode. Its military dispositions and weapons deployments are clearly guided by an offensive strategy and motivated by an offense-minded political intent. In a word, the Warsaw Pact does not prepare for defensive war because it does not expect to fight one.

We in the West must therefore adopt a strategy and military posture which offsets that of the Warsaw Pact while encouraging positive conditions for the political change that we favor. First of all, we must adopt a strategy that makes certain that Moscow's military planners could never confidently predict to the members of the Politburo that they would prevail in a military clash. But it also means that such deterrence must be achieved in a way that facilitates the favorable political trends discussed above.

As a practical matter both western Europe and the United States must do more. Specifically this country must devote its resources to its global responsibilities particularly by enhancing both airlift and sealift capabilities as well as central strategic forces. And western Europe must do more to provide for its own defense. Surely 374 million Europeans with an aggregate economy of $3.5 trillion -- faced with an opponent with 275 million people and a GNP of only $1.9 trillion -- should not need to depend for their defense as heavily as they do on 241 million Americans with a $4.2 trillion economy. Contrary to the doomsayers in the United States who have argued that any change in defense burdens would immediately precipitate a massive stampede in Europe toward neutralism, Europeans have responsibly taken up the question and have now started discussing how to strengthen their collective defense effort.

Beyond efforts to strengthen defense, however, we also need to work toward using arms control negotiations to encourage positive historical change. After the expected INF agreement, any future proposals for reducing the number of battlefield nuclear weapons must be linked with proposals for reducing the level of conventional forces. The threat of Soviet conventional forces, after all, was the reason NATO deployed its nuclear forces. It is, therefore, imperative that if we negotiate on one, we insist on concomitant progress on the other.

To do so effectively, western proposals must dramatize that aspect of the offensive Soviet conventional threat which is most easily understandable to the Europeans -- both in the West and in the East. Most of them have vivid historical recollections of massed offensive tank formations spearheading aggressive warfare. Accordingly, as I have written here before, western proposals should aim to thin out -- and eventually perhaps even remove -- Soviet main battle tanks from the heart of Europe. By focusing on hardware rather than manpower issues, NATO proposals might be able to overcome the difficulties that caused the balanced force reduction negotiations in Vienna to bog down.

Proposals for a tank thin-out or eventual removal should be paralleled by initiatives to engage eastern Europe in closer East-West economic cooperation, thereby also facilitating the region's desperately needed reforms. Vice President Bush's current trip to Poland offers a particularly timely opportunity to set in motion a process in which East-West economic initiatives are deliberately related to constructive internal changes.

Except for narrow-minded Stalinists, eastern European leaders know that the economic recovery of eastern Europe requires both such cooperation and basic reforms. We are thus at a very special historial juncture, pregnant with genuine opportunity for the West to move events in desirable directions. It can do so by fashioning a comprehensive strategy in which conventional arms reductions and wider economic cooperation become mutually reinforcing in their positive political effects.

Zbigniew Brzezinski was national security adviser during the Carter administration. His latest book is "Game Plan."