On Sunday, Oct. 1, an American newspaper began its report on a battle in Lebanon as follows: "Syrian peacekeeping troops pounded rightwing Christian militias in and around Beirut yesterday . . . in the worst explosion of fighting since the Lebanese civil war . . ." supposedly ended two years ago. This is at once a startling and a familiar sentence.

The terms have no relation to reality, yet they have become common-place. The invasion of Lebanon by Syrian and PLO forces becomes a Lebanese "civil war." The Syrian invasion forces become "peacekeeping troops." The people defending Lebanon's constitutional arrangements become "right-wing Christians."

This is but one unhappy example of a dangerous trend in the way we discuss political developments, especially in international affairs. Fred C. Ikle has coined the term "semantic infiltration" to describe it.

Simply put, semantic infiltration is the process whereby we come to adopt the language of our adversaries in describing political reality. The most brutual totalitarian regimes in the world call themselves "liberation movements"; it is perfectly predictable that they would misuse words to conceal their real nature. But must we aid them in that effort by repeating those words? Worse, do we begin to influence our own perceptions by using them?

In recent months, the foreign policy of the Carter administration has been bedeviled by a seeming inability to distinguish the proper meaning of political words.

During the summer, State Department spokesmen took to calling the pro-Soviet military organizations in southern Africa "liberation forces." Even as the State Department proclaimed its neutrality in the conflicts there, its very choice of words - its use of the vocabulary of groups opposed to our values - undermined the legitimacy of the pro-Western political forces in the area.

We pay for small concessions at the level of language with large setbacks at the level of practical politics.

There is no better illustration than the current controversy over the support the United Nations has been providing for the grotesquely misnamed Palestine Liberation Organization. The PLO operates at the United Nations under a "cover" voted for it back in 1975 - the "Committee on the Exercise of the Inalienable Rights of the Palestine People."

On June 28, the Senate, without a single objection, adopted an amendment I had proposed to reduce the American contribution to the United Nations by our proportionate share of the Palestinian committee's budget. The United States pays about a fourth of U.N. expenditures, so we were, in effect, contributing about $200,000 to a PLO organization whose principal purpose is the dissemination of vicious antidemocratic, anti-Israeli, anti-American propaganda. Just this month, 27 of my colleagues in the Senate joined me in a letter to the president urging, over again, that the funds be withheld.

To understand the committee, simply remember it was created by the General Assembly on Nov. 10, 1975, the same day of the notorious resolution declaring Zionism to be a form of racism.

That venomous episode, of course, was the most brazen and ominous instance of the perversion of language in recent memory. And so it was necessary to warn at the time that this was but the beginning, that the totalitarian states were succeeding in destroying the language of human and political rights, that the very states that were enthusiastic supporters of the Soviet-inspired resolution on Zionism would inevitably find themselves victims of the same tactic.

With depressing predictability, the U.S. Department of State chose not to see an issue where one was clearly present. Apparently, there is no inclination to raise this matter at the United Nations directly, and a wholly misleading calm thus settles over the organization.

What else happens during this supposed era of good feelings? One example: Just last month, on Sept. 12, the "Decolonization Committee" of the U.N.'s General Assembly voted 10 to 0 (with 12 abstentions) to condemn the relationship between the United States and Puerto Rico. The Cuban resolution declared the United States was guilty of colonialism in Puerto Rico, of stifling political expression, of holding political prisoners.

Now the 10 states who voted to condemn us were, without exception, dictatorial regimes - the Soviet Union, Iraq, Syria, Cuba, China, Bulgaria, Tanzania, Afghanistan, Chile, Czechoslovakia. All are guilty of what they falsely accuse the United States. Since when, for example, does the Soviet Union believe in the "inalienable right to self-determination and independence"?

For several years, I have maintained that we need to become far more sensitive to these distortions of political language that are everywhere around us.

The costs of inattention seem to escape even those among us who pride themselves on their "hardheadedness" in matters of geo politics and military strategy. Surely, Soviet gains in Afghanistan or in Ethiopia or in some other place are visible. Their gains in the realm of political discourse may be less obvious, but nonetheless important over the long term. Consider: When the question of Puerto Rico was before a committee of the United Nations, not one country concluded that its interests could be served by identification with the United States.

These episodes are not isolated events. Rather, they are inseparable from a larger process under way since totalitarian power became a major factor in world politics. The totalitarians seek to supplant the West's political culture with their own system. In order to do it, they understand they must seize the symbols and the vocabulary of progress.

The irony is that, while democratic symbols are far the most powerful in the world, the antidemocratic forces are somehow able to seize them, much as George Orwell described in his fable "1984."

Along about 1950, for example, Stalin's Russia had come almost to own the word "peace" in international debate. The more receptive the world becomes to Soviet linguistic imperialism the more will the nations of the world begin to accomodate themselves to Soviet strategic aspirations. In this way, the process of strategic accomodation can be effectively hidden - mostly from the future victims of Soviet imperial advance.

There was a time when the isolation of the Soviets and their sympathizers in the world body was one of the central facts of international politics. But precisely because of a peculair American insensitivity to the problem of "semantic infiltration" these past years, the situation is now reversed. International politics seems, increasingly to be a realm where totalitarian concepts of politics and economics are prominent if not dominant.

That the Soviets will seek to seize control of the language of politics is obvious; that our own foreign affairs establishment should remain blind to what is happening is dangerous.

We think of the U.N. Charter as a protection for us against possible aggressors. But the real value of the system is not so much to a great power like the United States, rich in resources and military potential, but to the small nations of the world that must ultimately rely on the protections the world community affords them.

I recall very well that, in Nov., 1975, the poor African country of Somalia sponsored the anti-Zionism resolution. Its co-sponsors were Cuba and Libya, and all acted on the behest of Russia. The government of Somalia was carefree, even arrogant, in the way it was willing to allow the United Nations to destroy the language of political rights.

But, in late 1977, Somalia itself became a victim of Soviet ambition - and theyeby a victim of its own willingness to distort the U.N. Charter. Indeed, when Somalia was bombed by the Soviet-made airplanes of neighboring Ethiopia in the name of "national liberation," no one seemed interested in Somalia's plight. And so it goes.

Yet there are opportunities for a reversal of these trends, but surely they require a willingness to recognize the problem.

It happens that tomorrow, the U.N. Educational, Scientific and Cultural Organization meeting in Paris, may well have the critical vote about the U.N.'s position on the "mass media." What is this about? For several years, the Soviets and their adherents have been attempting to secure passage of a U.N. declaration that would declare that governments have primacy in the matter of news reporting and news gathering.

Moreover, the draft declaration they originally prepared made it plain that the mass media have no true purpose save to advance the foreign policy objectives of the totalitarian states. It is, indeed, an outstanding instance of the process of "semantic infiltration"; the totalitarians seek to destroy freedom of the press by invoking the priciple of freedom of the press. That draft declaration thus became a threat to every news-gathering and news-disseminating organization in the free world. Efforts are under way to defang it, and tomorrow's scheduled vote may well determine their fate.

Meanwhile, the leaders of our communications industry remain far in advance of our government on these points. It is encouraging, for instance, that the five-person U.S. delegation to the UNESCO meeting includes a journalist, William Attwood, Newsday's board chairman. Publishers and editors from around the world increasingly have come to sense their common danger. There is, above all, in the American press, a fighting tradition that the totalitarian states will soon discover if they persist in provoking us.