Better that Leonid Brezhnev should be talking about peace than threatening war. But the Soviet leader's latest statement on disarmament and detente invites caution. It is clear Mr. Brezhnev is buttering up Europeans in advance of his important visit to Bonn later this month. By promoting a peace-loving image of the Soviet Union, he is also exploiting growing concern in Western Europe about what is perceived as the bellicose posture of the United States.
Most people will see through Mr. Brezhnev's propaganda ploy. But the question is: will Washington have the good sense to respond to European fears, however unfounded, by launching a ''peace offensive'' of its own? It can do so by publicly placing less stress on military rearmament and more stress on the US-Soviet arms control talks starting this month. Many West Europeans seem to think the US is half-hearted about these negotiations on theater nuclear weapons. The Reagan administration thus has an opportunity to show that it is taking them seriously - for example, by being as open as it can on its negotiating position.
This is not to underestimate the importance of bolstering NATO's defenses. The Russian missile buildup is dismaying. Mr. Brezhnev in fact performed some sleights of hand in his assessment of the East-West balance of power. He contends, for instance, that the Soviet Union has 975 medium-range nuclear weapons within 600 miles of Western Europe as against 986 NATO weapons facing the USSR. But these figures include US bombers in Western Europe and on aircraft carriers while excluding the Soviet counterparts of equivalent range (which outnumber the Western planes). Mr. Brezhnev, moreover, does not include Soviet missiles stationed east of the Urals and still capable of hitting Western Europe. The count made by the respected International Institute for Strategic Studies in London shows a decided imbalance in favor of the Warsaw Pact.
Hence President Reagan cannot be faulted for following up on the decision of the previous administration to push ahead with production and deployment of new advanced medium-range missiles in Western Europe - a move the West Europeans themselves proposed. But in the process of military preparations the US has unnecessarily risked feeding the pacifist, antinuclear mood in Europe. It is a matter of public style and tone. If the US wants to be seen as tough and businesslike in its dealings with Moscow, it surely does not want to be seen as belligerent and unrea-sonable.
There is evidence the administration may in fact be consciously moderating its posture. Secretary of State Haig, in testimony before the Senate, has taken pains to convey that in the event of a conventional war in Europe the US and its allies would do everything to avoid a nuclear exchange. Such a clash, the secretary said, would be a ''no-win proposition.'' He thus seems to echo Mr. Brezhnev's own scorn of the idea that a limited nuclear war is thinkable.
Not unrelated to assurances on the nuclear front is also a shift toward a more balanced US stance on some political and economic questions. Mr. Reagan could not, for example, have been unmindful of trying to please his allied partners as well as the third world by adopting a nonconfrontational approach at Cancun. Or take the sensitive matter of human rights. The State Department has issued a memorandum arguing - rightly, we believe - that the US cannot offer a credible alternative to Soviet communism or ''neutralism'' in Europe unless it takes a forceful position on political freedom and civil rights. This is in marked contrast with earlier impressions conveyed by the Reagan administra-tion.
We hope we are right in detecting an administration effort to respond to concern abroad about Washington's overemphasis on the military buildup. There is no doubt of the need to ''resell'' the Atlantic alliance to a new generation of Europeans by reminding them of its value to stability and peace for more than three decades - as well as of the dangers which would confront Europe in the absence of a collective security system. But this can be more readily accomplished if the centerpiece of US policy is seen to be a determined effort to restrain the nuclear arms race - rather than military preparations that could tend to escalate it.
Mr. Reagan should head Mr. Brezhnev off at the pass.