BETWEEN the Tet offensive in Vietnam and the siege of the U.S. embassy in Tehran, America has been in confused retreat. The root causes of our mounting troubles abroad are to be found not in remote Iran or Soviet-occupied Afghanistan, but here at home. The American retreat from world leadership and respect began inside the heads of influential and articulate citizens who drew and taught, especially through the news media, the wrong lessons from the past decade of U.S. defeat.

Before we can reverse this downtrend, we must identify and begin to correct at least some of these false ideas. If we do not, the American retreat will continue until the globla primacy of the Soviet Union becomes certain in the 1980s and beyond.

What's gone wrong? Here are several trends to be reversed: 1. The ascendancy of Congress

Seen in historical and strategic perspective. Watergate was the climax of the domestic political civil war fought to determine who would explain America's defeat in Vietnam and who would be blamed for it. Congress won this conflict and imposed punitive ex post facto restrictions on the office of the presidency in the conduct of foreign policy. Antiwar left-liberals in the Congress and their news media sympathizers invented the myth of the tyrannical "Imperial Presidency" and the countermyth of the prescient, populist Congress.

In fact, the United States lost in Vietnam because the war was fought for incoherent political reasons and under extreme tactical constraints ("graduated response") that made it militarily unwinnable. It was the first time in history that blood was spilled according to the "limited war" theories of certain "defense intellectuals," as well as the first war to be shown nightly uncensored on the nation's living room television screens.

In the end, the antiwar liberals succeeded in turning the partisan tables and made Richard Nixon the scapegoat for Lyndon Johnson's and Robert McNamera's war. They also imposed on America as a whole the burden of guilt for waging an "immoral" war. The simplistic slogan "No More Vietnams" became the justification for a wide array of misguided "reforms" giving Congress far-reaching authority over foreign policy, intelligence-gathering, covert activities, use of U.S. armed

As a result, U.S. foreign poicy is now dictaed by Congress, an inherently parachial and increasingly undisciplined and anarchic body. A committee of 535 self-employed political entrepreneurs cannot agree on when to go to lunch, much less where U.S. foreign policy should be steered and by whom. As long as the "Imperial Congress" possesses unchecked power to obstruct, delay and virtually paralyze the exercise of positive presidential leadership, U.S. foreign policy will remain more or less disastrous.

The remedy: A stong, purposeful president, prepared to take his arguments for the national interest over the heads of Congress directly and persuasively to the people. Runaway public-sector growth

Since the Great Society was launched more than a decade ago, we have created the opportunity for congressional government to practice cash-and-carry democracy consisting of the lavish care and feeding of fiscal constituencies. We have thus established a absolute domestic policy priority, making it extremely difficult to divert resources to meet urgent foreign policy and defense needs.

More than 54 percent of the American population now receive salary or "transfer payment" checks from some level of government, mostly funded by Washington through ever-higher taxes and inflation. Overall, public sector spending claims one-third of the gross national product. Domestic programs calculated to bribe various groups of voters with their own taxes have grown relentlessly while real defense spending has shrunk to pre-World War II levels as a percentage of GNP.

The remedy: "Recorder priorities" and give a closely supervised Pentagon the sources needed to rebuild the strength and credibility of U.S. military power. Economic and monetary isolationism

We have kept our economy expanding and paid skyrocketing OPEC oil prices by printing more and more dollars. One of the unforeseen effects has been to undermine our world economic leadership and drive the United States toward isolationist policies, such as possible foreign exchange controls.

Few American politicians yet understand, much less accept, the loss of U.S. economic polity-making autonomy as the result of chronic high inflation and weakness of the dollar abroad. Foreigners holding hundreds of billions of dollars have demanded that the United States accept the discipline of defending our currency against collaspe through high domestic interest rates, despite the recessionary impact on the U.S. economy.

But the austerity policy of "the dollar first, America second" lacks congressional and popular support, as the anticipated recession and the next dollar crisis will reveal.

The remedy: Before Federal Reserve Chairman Paul Volcker is forced to stand alone, restoration of the dollar's international standing and America's influence should be given the top priority it deserves. Self-deceit on U.S.-Soviet relations

Since the mid-1960s, a formidable bipartisan consensus has formed in political, intellectuala and media circles: The Cold War is "over," the Soviets need and want arms control agreements ("peace") as badly as we do, and therefore Soviet intentions should be optimistically construed. The corolary, of course, was that the Soviets, regardless of what they or their clients and proxies said or did, sincerely wanted "detente" and improved relations, concretely expressed in the sale of American grain and technology on favorable terms.

From cuba to Angola to Afghanistan, the United States has learned the habit of self-restraint in all circumstances so as not to jeopardize ongoing SALT negotiations, upset detente and the assumed Pax Atomica, and call into question our politically comfortable emphasis on expanding welfarism at the expense of the defense budget.

Because the Cold War was authoritatively said to be "over," and the marlevolent roles of the Soviet Union and the KGB have been neglected in polite company, the United States appeared to have no enemy to blame when it suffered defeats, reverses and setbacks. Mounting American failure and frustration merely intensified the bogus post-Vietnam sense of guilt and the reflexive aversion to the exercise of national power. Were we have only ourselves to blame for our plight.

The remedy: Open both eyes wide, find Afghanistan on the map and ponder the geopolitical consequences of its conquest by the Soviet Union, for which the Cold War never really ended and the era of "detente" therefore never began. 5. Disrespect for political uses of power

Military power is useful and necessary to make possible the fulfillment of America's moral ideals -- and, in any event, to ensure their survival in the face of hostile forces and heavily armed anti-ideals such as Marxism-Leninism. Yet, since the early 1970s, the United States has behaved as though our declining power had no real purpose anyway and the simultaneous massive Soviet military buildup posed no real threat. Even those who knew better engaged in such expedient sophistry.

For example, former Secretary of State Henry Kissinger, in rationalizing the United States' disguised acceptance of strategic inferiority, made it sound as though the two nuclear superpowers could escape the gravitational pull of history. After the initial SALT agreements were signed, he told congressional leaders:

". . .throughout history, the primary concern of most national leaders has been to accululate geopolitical and military power. It would have seemed inconceivable even a generation ago that such power once gained could not be translated directly into advantage over one's opponent. But not both we and the Soviet Union have begun to find that each increment of power does not necessarily represent an increment of usuable political strength . . ."

Kissinger failed to produce, then or subsequently, any evidence of the Soviets' alleged "discovery" that their increasing power is politically useless. And their contrary behavior, as their military strength and confidence have grown, utterly refutes him.

Just as increasing military power can be used to achieve expanding geopolitical influence, as the Soviets have repeatedly demonstrated, so the American decline in the 1970s surely proves the opposite is true. Nevertheless, one of the most pernicious false lessons of the Vietnam era is the notion that passivity is a viable and rational policy "option," and that doing nothing but moralizing in the face of a clear and present danger will impress friend and foe alike with our leaders' virtuous "self-restraint." On the contrary, it convinces them that America is blind to its national interests and unable to defend them.

The remedy: The president might get angry -- just once -- and then do something immediately relevant to the objective at stake.

The seige of the U.S. embassy in Tehran marks a potentially climactic turning point in the long American retreat. The Ayatollah Khomeini, a villian straight out of the pages of World War II-vintage comic books, has broken the spell of complacency and fired the mass imagination -- at least temporarily. The public's capacity for patriotic indignation has not atrophied. But the evident aim of Carter administration has been to dampen this anger and not direct it toward constructive long-term objectives. The human ordeal of the hostages in Tehran will have been utterly in vain if this sad, potentially constructive episode ends with their release, our nation's humiliation and much televised hugging and kissing while the president beams.

Henry Kissinger and James Schlesinger have been friendly rivals and frequent policy debaters since their Harvard days. Now they sit under the same roof (in unmarked suites on separate floors) in the downtown Washington office building housing Georgetown University's Center for Strategic and International Studies. Those who talk privately with thest two strategists find they agree on a grim central propostion: In the early 1980s, the decline of American power could gain irreversible momentum, leaving the Soviets as the only truly global force in world politics.

The Soviets, with their failing economy, inefficient agriculture, social and ethnic tensions and uncertain post-Brezhev succession, are scarcely invulnerable. But they cannot fail to win a contest in which they are without a competitor. This is the question at the heart of the 1980 presidential campaign: Does the United States have the will -- even the sense of growing national danger -- to reenter the strategic arena and commit the resources demanded for survival and success in the long pull?

Kissinger, Schlesinger and other senior analysts who form a small but extremely well-informed community of the concerned know the worst, on the best authority, and they are the most pessimistic. As many members of this foreign policy inner fraternity see it, Carter, the devout noninterventionist, faithfully represents America's traditional yearning to be free of dangerous foreign entanglements. On the campaign stump, he will be able to use the most powerful emotional formula in American politics: "I kept our country out of war."

Yet, even the most pessimistic observers concede, all is not doom and despair. Much that has gone wrong since the fall of Saigon is being set right, and they cite these actualand potential positive trends: 1. The revolt of the "Defense Democrats"

The end of the post-Vietnam era of self-disarmament is signaled by the emergence of an influential bloc of moderate Democrats in the Congress who demand increased defense spending, especially to create the mobile forces needed to intervene in a future crisis in the Middle East. Sen. Ernest F. Hollings (D-S.C.), chairman of the defense subcommittee of the Senate Budget Committee, is a leading figure. He calls for "an end to the SALT mentality" that has sapped U.S. willingness to preserve military parity with the U.S.S.R.

As the pro-defense consensus forms in Congress, its supporters will also tend to argue for restoring the legitimate authority of the Watergate-weakened presidency in various aspects of foreign policy, incuding intelligence and covert CIA activity, provided the incumbent in 1981 knows how to use such power. 2. Revival of the teaching presidency

The presidency remains a "bully pulpit." In the television era, most Americans form their impressions of their leaders and the country's condition from what they see and hear on the tube. Carter uses the medium of mass instruction so poorly that he drains vitally important subjects of relevance to the lives of ordinary citzens. As a result, the screen has been dark during his inept presidency, and the actual and prospective consequences of the American retreat have gone largely unappreciated by the public.

In contrast, Sen. Edward Kennedy and the Republican front-runner, Ronald Reagan, are much more skillful and exciting TV performers. Their attacks on Carter and his policies, though aimed from opposite ideological poles, will converge on the theme of American weakness, helping to awaken the dozing electronic electorate. Though their policy prescriptions radically differ, the telegenic politicians will set the campaign agenda for debate on America's foreign policy and defense preparedness -- even if the result of the debate may be Carter's renomination and reelection. 3. Rise of a new American consciousness

A future defense-minded president who uses TV more effectively than Carter at least will have the chance to justify the need to redirect resources and make the sacrifices required to rebuild U.S. military power and influence aboard. He will have to appeal to virtually the only reason that may penetrate the bone-deep skepticism of contemporary American opinion -- the urgent need to defend concrete national interests, such as continued access to Persian Gulf oil imports essential to prevent U.S. economic collapse.

At the threshold of the 1980s, a new American consciousness is forming: It is more sophisticated, realistic and pragmatic than a decade year ago, and more cynical, too. It is anti-idealistic and anti-crusading, but it is assertive and quick to defend what it prizes. Foreigners soon will encounter a new breed of Americans who think and behave as selfishly as they do, a solid foundation for a durable, long-term U.S. foreign policy based on genuine interests, not mere sentiments. 4. Allies are discovering their strengths

From London to Bonn to Tokoyo, as Washington has become more unpredictable and less dependable, allies are belatedly discovering their untapped strengths and their capacity to defend themselves. Sometimes, as in the case of competitive petro-diplomacy, such pursuit of national self-interest is shortsighted and threatens to further weaken alliances. But there is a positive side to the new self-assertion.

Japan is at last seriously planning for its own self-defense. The nation with the second largest GNP in the noncommunist world now spends less than 1 percent of its output on its defense budget. Clearly Japan can afford to do much more. Using U.S. blueprints, for example, Japan might build a fleet of perhaps 50 modern antisubmarine vesssels -- clearly useful only for defnsive missions -- and then "lease" the fully manned ships to the United States for a nominal sum in a manner reminiscent of the pre-World War II destroyer deal between the United States and Britain. To allay possible fears of Japan's possessive smaller neighbors, this fleet might be operated under joint command. Building naval ships would also be a sensible way to use Japan's idel steel-making capacity and fill its empty shipyards. 5. Rediscovery of the Cold War

One-sided detente is finished politically. The Senate will tacitly abandon the SALT II treaty and the self-paralyzing from which it came, as Sen. Hollings and others urge. Increased defense spending will be justified by the renewed Cold War, which, it will be discovered, did not end after the nerve-testing 1962 Cuban missile crisis but only took a turn that was misunderstood at the time. From that crisis the Soviets drew the lessson that strategic inferiority leads to political-military defeat. They resolved not to be humiliated and forced into retreat again. Their brutal and arrogant displays of raw power from Angola to Afghanistan are now pushing the United States toward the same resolve.

To rebuild, U.S. military strength, former Defense Secretary Schlesinger urges the committment of an additional 1 percent of GNP, or $25 billion, annually to the defense budget in the 1980s. Behind such a commitment would lie the most profound change in the way Americans see the world and themselves since the dark early 1940s. These, too, were initially years of retreat but the angry memory of Pearl Harbor insured an all-out commitment to dig in and take the offensive.

Will the American retreat end without another Pearl Harbor? Or are we already experiencing the contemporary geopolitical equivalent of that galvanizing disaster on the approaches to the oil-rich Persian Gulf? In any event, we should not wait for World War III to be formally declared before we acknowledge it and recognize that we are losing it.