The problem with allowing cold war rhetoric to dominate the US public posture is that it begins to run out of control. That is what happened when a US Army general on the National Security Council staff took it on himself to declare that ''the Soviets are on the move, they are going to strike.'' The pronouncement is shocking and patently false. The White House acted with proper alacrity in reas-signing the general.
However, the American public would be even more reassured if the President made a firmer disavowal of General Schweitzer's grim words. The danger of allowing such loose talk about ''Soviet nuclear superiority'' and a ''drift toward war'' to gain currency is that people begin to believe it, and to plan for it. Feeding a war scare does untold harm in trying to plan rationally and soberly for the nation's security.
In the wake of the incident, many will ask: is the United States dwelling too much on the buildup of military might and potential nuclear confrontation with the Soviet Union to the neglect of the pursuit of arms control and the prevention of war? The West Europeans, especially, are even more skeptical about Washington's intentions now that Mr. Reagan has commented that it would be possible to use tactical nuclear weapons in Europe without inviting an all-out nuclear exchange - thus allowing the interpretation that the US might use Europe as a battleground to avoid a Soviet nuclear attack.
No doubt the President's remarks have been blown out of proportion, as the secretary of defense says. But there is today too much emphasis on fighting a ''limited nuclear war.'' Such an idea began to acquire credence a few years ago - in the days of James Schlesinger - and now appears to be an integral part of US defense strategy. Certainly military policymakers have to make plans for all sorts of contingencies. But more restrained and subtle utterances on such a horrifying topic would avoid generating public alarm. All that the recent talk does is fuel anti-nuclear sentiment in Europe and persuade many Europeans they should not accept the NATO plan for deploying new theater nuclear weapons in their backyard. Few people in the high commands of the military, morever, believe that a nuclear war could be contained. Nor do they believe that implied threats to use nuclear weapons as an instrument of political power would lead anywhere but disaster.
Instead of focusing so single-mindedly on the ''negative'' theme of the Soviet threat, the United States would gain more credibility abroad by demonstrating its commitment to the ''positive'' theme of nuclear arms talks. Negotiations over theater weapons are due to begin in November. So far there is no inkling what administration thinking on this extreme complex subject is, and no sign that a well-thought-out negotiating position is emerging. The impression conveyed in fact remains one of uncertainty and confusion behind the scenes - an impression bolstered by outbursts such as that by General Schweitzer.
President Reagan, in fairness, has had his hands full dealing with the economy and with such diplomatic problems as the Middle East and the Cancun conference on global poverty. Once that conference is over, however, it is to be hoped that he tackles in earnest what should have the highest priority: beginning a serious effort with the Russians to restrain the nuclear arms buildup and to reduce the possibility of war. It is ironic and not a little sad that the Soviet Union, armed to the teeth, is winning propaganda points by appearing to be an advocate of peace while the United States is alienating friends and allies because of its ''hawkishness.'' Washington should want to - and can - reverse that perception.