A new `d'etente' for the 1980s. Soviets and Americans are now engaged on wider range of issues

Needed: a new word for ``d'etente.'' Diplomatic specialists and Reagan officials toy with alternatives such as ``d'etente II'' or ``engagement'' or such an ungainly phrase as ``carefully engaged on a broad agenda.''

A lively, crisp substitute that grabs headlines has yet to be found. But, as President Reagan leaves tomorrow on the first leg of his journey to Moscow, he and his aides are confident that United States-Soviet relations today are based on a realistic, hard-headed approach that is markedly different from the style of d'etente initiated by President Nixon in the early 1970s.

Not everyone agrees with that assessment. But some who were involved in the Nixon policy point up the differences, including the extent to which the Soviet-American dialogue has broadened and deepened.

``You are seeing a degree of engagement on a range of issues such as we have not had before,'' comments Helmut Sonnenfeldt, a former aide to Henry Kissinger.

Today Washington and Moscow are talking about arms control issues that go further than anything proposed under the Carter administration, Mr. Sonnenfeldt says. They are also talking about regional conflicts around the world that 14 years ago, when Mr. Nixon and Leonid Brezhnev held a summit in Moscow, ``would not have been given the time of day.''

Further, the two sides are dealing with all manner of human rights issues, from Jewish emigration and political prisoners to news media access and freedom of religion. In the '70s, says Sonnenfeldt, ``it wasn't possible to talk about religion or psychiatric wards.''

As they head for the Soviet capital, Reagan administration officials point with satisfaction and even a degree of amazement to the improvement of US-Soviet relations along a broad front of issues.

On arms control, there will be no signing of a strategic arms agreement in Moscow, but the two sides have already signed the first treaty ever to eliminate a whole class of nuclear weapons (the INF or Intermediate-Range Nuclear Forces Treaty). And significant headway has been made toward a treaty reducing strategic or long-range nuclear weapons.

The door is also opening to serious possibilities for reducing conventional forces.

Soviet withdrawal from Afghanistan is the most significant development of the expanding dialogue on regional issues. But the Soviets are now engaged in discussions about other areas of the world where the Soviet presence also concerns American policymakers. Among them are Angola and Cambodia, where Moscow appears ready to cooperate in the resolution of conflicts.

Progress is also recorded in the area of human rights, as measured against obligations under the Helsinki Accords of 1975. Emigration of Soviet Jews, Armenians, and Germans is on the rise. Numbers of political prisoners have been released. Most significant, US officials stress, is the fact that human rights problems are now routinely and candidly discussed, even at the leadership level.

With respect to bilateral relations, Moscow and Washington have revived the framework of cooperation set up during the Nixon years. Experts from the two sides meet regularly to discuss projects in such areas as health care, space research, nuclear energy, the environment, and housing. Cultural exchanges have returned to the level of the 1970s.

What accounts for this growing US-Soviet accommodation is a matter of viewpoint. Many in the Reagan administration ascribe it to the tough, persistent approach of the President, who waited until he had revitalized US defenses before abandoning his ``cold war'' rhetoric and doing business with the Soviets.

But administration officials acknowledge that the advent of a new and vigorous Soviet leader has also made the improvement of relations possible. Driven by a need to tackle their severe internal problems, Mikhail Gorbachev and his Politburo supporters are calculatedly scaling back Soviet commitments abroad and opting for greater cooperation with Washington.

Thus, while US and other Western aid to the Afghan rebels clearly raised the cost to the Kremlin of continued occupation of Afghanistan, it was Mr. Gorbachev's readiness to accept a politically embarrassing Soviet retreat that was crucial.

In the 1970s, diplomatic analysts note, the Brezhnev regime regarded better relations with the West as a substitute for attacking the fundamental problems of the Soviet system. And, taking advantage of America's weakness and uncertainty after the Vietnam war and the Watergate scandal, the Soviet Union embarked on an expansionist policy abroad that eventually undermined d'etente.

Today, experts say, the US itself is stronger internally, and the base on which it is pursuing an accommodation with Moscow is more mature. Disappointed by the '70s version of d'etente, it is pursuing relations with a greater sense of realism about what can be achieved. The fact that the Reagan right sought - and failed - to achieve US military superiority has contributed to this realism.

Whether ``d'etente II'' can withstand the unpredictable vicissitudes of the relationship and the conflicts bound to arise between adversaries remains to be seen. John Steinbruner, director of foreign policy studies at the Brookings Institution, suggests that it is not the preferences of Mr. Reagan or of Gorbachev that are driving the current thaw, but ``an underlying logic'' of mutual interest that is forcing the leaders to respond.

``It's an interaction between the personalities and substance,'' Mr. Steinbruner comments. ``People are not going to drive just by their own individual convictions, be they a president or a Communist Party general secretary. ... The events come out of the mutual interests of the two countries.'' Both nations, he says, need a regulated, peaceful relationship.

``The US and the Soviet Union clearly have ... a considerable stake in maintaining this version of d'etente,'' says Harold Brown, former secretary of defense. ``This particular summit ... is symbolic in the sense of a clearly anti-Soviet President putting his seal of approval on a form of d'etente ... and an emphasis on the cooperation part of the cooperation-competition dichotomy that characterizes US-Soviet relations.''

But diplomatic experts in and out of government worry that the growing improvement of relations could again generate a sense of euphoria, as happened in the '70s, and weaken American detemination to remain militarily strong. Dr. Brown notes, for instance, that the ``economic excesses'' under the Reagan administration will force a reduction of defense programs for some years to come which could benefit the Soviets and pose problems for the next US president.

``It's hard for us to remain vigilant and cautious ... in the face of Soviet smiles,'' comments Lt. Gen. Brent Scowcroft, national security adviser in the Ford administration.

At the same time, it is recognized that the US-Soviet relationship is a fragile one. Unforeseen developments, such as an escalation of turmoil in Eastern Europe, could lead to a breakdown of the process.

``During these times of trouble in Poland,'' says Arthur Hartman, former US ambassador to Moscow, ``it would only take a major intervention by Polish troops ... to throw the damn summit right out the window. So I think it's that fragile.''

``I think it's perhaps a little less fragile in the sense that there are forces in Eastern Europe that know what the limits are ... but these things can get out of control,'' he says.

Second of a series. Next: the summit agenda.