IN RECENT years American views of the Soviet Union have undergone significant change. In the late 1970s the Soviet Union was seen as a country bent on the relentless expansion of its military power and global influence. Now the belief has gained ground that the Soviet Union's ambitions have outstripped its power, and that, far from being on course to achieve world domination, it is in the grip of a profound domestic crisis. In his new book Richard Pipes, an eminent historian of Russia who served as director of East European and Sovit affairs in the National Security Council in 1981-82, takes the contradiction between the Soviet Union's global pretensions and the economic and political basis of its power as his central theme.

Pipes' main thesis is that the Soviet threat to the West -- its drive to establish world hegemony -- is rooted in the Soviet system itself, and that it will not diminish until and unless that system has undergone substantial change in the direction of democracy. He argues that serious economic and political crises are pushing the Soviet Union towards reforms in which the nomenklatura -- the privileged political-scientific class -- will have to loosen its grip on power and permit far- reaching changes in the system. He urges the West to adopt policies that will help the forces of change inside the Soviet Union.

The West can do this, Pipes says, by neutralizing the Soviet military threat, by restricting the Soviet ability to interfere in Western politics, and by controlling the flow of Western technology to the Soviet Union. Because diplomats are, in Pipes' view, incapable of understanding totalitarian states, the formulation and execution of U.S. policy towards the Soviet Union should be the responsibility not of the State Department, but of the National Security Council.

Pipes complains with some justice that the Soviet Union is often treated tangentially in American discussions of Soviet-American relations, as though the really important arguments and conflicts were those that took place in Washington. He argues that, because Soviet international conduct can be understood only if it is seen as the product of the Soviet internal order, the state of the Soviet Union today must occupy a central place in any discussion of American policy. In seeking to change the focus of the debate Pipes shifts attention away from the purely military aspect of the Soviet-American relationship to its broader political context. This is the right way to present the issue, but there is much to question in Pipes' analysis.

Pipes is remarkably confident that the Soviet Union is in such a state of crisis that drastic change must come; that this change will take the form, not of collapse or foreign adventurism, but of reform; and that reform will result in legality, private enterprise and decentralization of power in Soviet society. Yet each of these arguments is open to serious doubt. The Soviet leaders do indeed face serious problems at home and abroad, but they may decide that they can muddle through by moderating their ambitions abroad and introducing piecemeal reforms at home. If the crisis did become acute, then it is possible that, rather than tackle the difficult issue of reform, they would decide on foreign adventures to distract attention from domestic problems.

IF THE Soviet Union does indeed turn inwards to deal with its domestic problems, this may not lead to the kind of reform that Pipes -- and most people in the West -- would like to see. Pipes cites the reforms in post-Mao China as a pattern that the Soviet Union might follow, but the analogy is not necessarily a good one. China's turning-inwards began with the Cultural Revolution, and it was only after the upheaval and chaos of those years -- something that one would not wish upon the people of the Soviet Union -- that the reforms of recent years were instituted.

If the West wants to encourage democratic reform in the Soviet Union, what should it do? Pipes' answer is essentially that it should try to exacerbate the crises that are pushing the Soviet Union in that direction. He takes the view that the Soviet Union's foreign conduct springs only from its internal order, and that if the West is merely conciliatory, the Soviet leaders will regard this as weakness and try to take advantage of it. But Pipes' analysis almost completely ignores the effect of external factors on Soviet policy. If the West tries to put intense military and economic pressure on the Soviet Union, the Soviet leaders may believe their security to be threatened and respond with repression at home and aggression abroad. This means that the problems facing Western policy are more complex than Pipes suggests.

Pipes argues that an effective embargo on technology transfer to the Soviet Union would do much to sharpen the economic crisis there and thus to hasten reform. (He upbraids the West Europeans for not being willing to go along with this idea, but his case would carry more weight with Europeans if he had advocated a grain embargo as well, for they will see this omission as a sign that Pipes wants Europe to bear costs that he would not impose on the United States.) Pipes is right to say that it does not make sense to sell military or dual-use technology to the Soviet Union, but he overstates the effect that even a leakproof embargo (assuming it were possible) would have, because he overestimates the role that foreig technology -- important though it has been -- has played in Soviet economic development and military power.

In general, although Pipes has many interesting things to say about the Soviet Union, he presents too optimistic a picture of the possibility of change and of the West's ability to influence its direction. This could be harmful if it distracted attention from the problem of conducting relations with the Soviet Union as it now exists, and gave rise to dissension among the Western allies.

As Bernard Weisberger's book on American policy towards the Soviet Union since the Second World War makes clear, it has proved very difficult for the United States to devise an effective policy towards the Soviet Union. A postwar consensus, based on the idea of containment, provided guidelines for policy into the 1960s. For a short while d,etente too commanded widespread support. But no consensus now exists, and the sour comments that Pipes makes in his book about major sections of American opinion are symptomatic of the bitter policy disagreements of recent years.

Weisberger provides an immensely readable account of Soviet-American relations since the Second World War, as seen from the American side, and of the repercussions of the Cold War on American life. He does not try to chart the way to a final settlement of the Soviet-American conflict, but puts his hope rather in the instinct for survival that exists on both sides.