When Secretary of State George P. Shultz presented his opening testimony on foreign assistance to the House Foreign Affairs Committee in February 1983, he spoke of the "vital" importance of the Persian Gulf to "the economic and political security" of the free world.

To make the point, he presented a color-coded map showing U.S. aid recipients in blue, the Soviet Union and its friends in red and pink, and a big gray arrow -- "Persian Gulf access" -- stretching across North Africa and the Middle East to its target in the center of the strategic waterway.

Three years later, on Feb. 5, Shultz gave a fresh interpretation of the U.S. world view in his opening presentation on the same subject to the same committee. This time he did not mention the Persian Gulf or even the Middle East, except in reference to the problem of international terrorism.

Shultz's remarkable omission is one of many signs of changing times brought about by the oil glut and the headlong tumble of petroleum prices from a high of $34 a barrel of crude oil in 1981 to a current spot price of about $16. This new era, which promises an economic boon to many oil-consuming nations and economic woe to many oil-producing nations, is altering the United States' global priorities.

When Middle Eastern oil producers seized control of the international energy market and quadrupled oil prices in 1973, and when the fall of the shah of Iran in 1979 led to redoubling of oil prices and long lines at American gas stations, the Persian Gulf was transformed into a top priority for American policy-makers.

The United States had relied first on Britain and later on Shah Mohammad Reza Pahlavi to police this faraway part of the world on behalf of the western allies and Japan. Suddenly the allies' security interests were in jeopardy, and there was no one besides the United States to assume the responsibility.

The ensuing sense of crisis led to unprecedented U.S. activism in Middle East politics, the wooing of key Arab countries with enormous sales of sophisticated arms, warnings to the Soviet Union that a U.S. "vital interest" existed in the Persian Gulf and creation of a U.S. military force whose mission was to intervene swiftly and effectively in any future emergency to secure the oil fields halfway around the world.

That period of activism has ended; the American approach to the region is again typified by passive diplomacy. Evidence of the change is easy to find:

*In the first three years after the 1973 oil crisis, Secretary of State Henry A. Kissinger visited Saudi Arabia 13 times. In contrast, Shultz in 3 1/2 years has visited the kingdom only twice, in April and July 1983. There have also been markedly fewer visits by other top U.S. officials.

*From the 1973 Middle East war through the signing of the Israeli-Egyptian peace agreement in 1979, the United States under Presidents Richard M. Nixon, Gerald R. Ford and Jimmy Carter was the driving force of the Middle East peace process. But, except for one brief sortie into the world of Mideast diplomacy with his September 1982 peace plan, President Reagan and his senior aides have let the Middle East countries themselves set the pace in the drive for regional peace, and the pace has been sluggish.

*In 1978 and 1981, Carter and Reagan committed their prestige and political resources in all-out struggles in Congress for approval of major sales of military aircraft to Saudi Arabia and other Mideast countries. The presidents won the day in Congress after two bruising battles with Israel and its friends in Congress. But in 1985 and 1986, with fewer lawmakers worried about oil supplies and large numbers backing Israel, Reagan saw little chance of winning approval for more modest arms sales to Saudi Arabia and Jordan; he gave up without a major fight.

The "Carter doctrine" enunciated in January 1980, the month after the Soviet invasion of Afghanistan, threatened a direct U.S. military response to attempts "by any outside force to gain control of the Persian Gulf region." It has lapsed, at least in U.S. public statements. In contrast, the "Reagan doctrine" of 1985 and 1986 is a declaration of support for anticommunist "freedom fighters" in a variety of third-world conflicts with no hint of direct U.S. military involvement and no connection to the Middle East.

*The Rapid Deployment Force, since renamed the Central Command, was established in March 1980 to back the commitment of the "Carter doctrine." While the Reagan administration continues to build up this force, it has yet to develop the logistical base or the unrestricted access to the region that planners say are essential to fulfillment of its mission.

*A final index of the fading concern about energy security for the United States is the administration's decision to stop adding to the Strategic Petroleum Reserve, which was once a high priority program. After spending $16 billion to fill Texas and Louisiana salt caverns with nearly 500 million barrels of oil -- enough to meet U.S. needs for about four months in an emergency -- the administration's proposed budget for fiscal 1987 includes no new funds for further purchases.

A number of elements underlie these shifts in emphasis, but there is little doubt that the dramatic change in world oil is central.

In 1977 the United States was importing four out of every 10 barrels of oil consumed in the domestic economy, and 2.8 of every 10 imported barrels originated in the Persian Gulf. Saudi Arabia, the largest single source of U.S. imports, was supplying more than 1.3 million barrels per day via an armada of oil supertankers.

Last year, according to government data, the United States was still importing about three of every 10 barrels of oil to turn the wheels of industry and the nation's automobiles and trucks. But its dependence on Persian Gulf nations had plummeted to less than half a barrel of every 10 imported. Saudi Arabia supplied just 93,000 barrels per day, only 7 percent of the level of eight years previously.

Realizing the dangers of reliance on a faraway and volatile part of the world, the United States set out to reduce its dependence on Middle East oil. Increased energy efficiency and new reliance on alternative types of energy have made it possible for imports to drop while the economy picked up, and the growth of oil production in almost every other area of the world including Mexico and the Alaska slopes has further reduced U.S. dependency on the Middle East. At the same time, a new network of overland pipelines from the Persian Gulf to the Mediterranean and the Red Sea has lessened the danger from a blockage of tanker traffic through the Strait of Hormuz.

"We've gone from a period of extreme vulnerability and dependence to a situation of much greater security," said E. Allan Wendt, deputy assistant secretary of state for international energy and resources policy. "Now with oil prices dropping, there is a temptation to be complacent."

But Wendt is one of many specialists who warn that today's situation may not last. "Probably," Wendt said, "the industrialized world will be much more dependent on Persian Gulf oil in the 1990s than we are today." That is because most of the world's untapped oil reserves are in the Persian Gulf. They are the resource of last resort as other sources of petroleum are slowly depleted and world consumption rises in the years ahead.

"The United States and the West alternate between panic and complacency," said James R. Schlesinger, who has served as secretary of energy and secretary of defense. "If we are a barrel short worldwide, we talk about shortage; if we are a barrel over, we talk about glut."

Schlesinger said the "perceived importance" of the Persian Gulf and Middle East has decreased more than has their real importance. "We are still dependent on those areas, but not to the degree we were before," he said.

William B. Quandt, who was National Security Council staff specialist on the Middle East under Carter, said: "We are seeing some of the consequences of the perception that oil is no longer as strategically important to us as it was." Among other indications, he said, is "the unwillingness of the United States to take the extra step in the Middle East peace process. This reflects the precept that no vital interest is at stake. People have a hard time convincing themselves why we ought to bother."

Zbigniew Brzezinski, the national security affairs adviser who popularized the notion of an "arc of crisis" centered in the Persian Gulf and who was a prime mover behind the "Carter doctrine," said "the strategic dimension hasn't altered that much" for the United States. He noted that key U.S. allies, including Japan and Western Europe, continue to be highly dependent on Persian Gulf oil even though the U.S. dependence has been reduced. (Japan imports 60 percent of its oil from the gulf, Western Europe about 25 percent.) Brzezinski said that "the glut, like what preceded it, is likely to be transitory, and then it is back to higher prices."

The sudden changes in America's relationship with the gulf have left scars on both sides. The 1970s were the first time since the United States became a great power that the country found itself so painfully dependent on other nations for a vital resource, and -- it seemed to many -- forced to adopt a political agenda imposed from the outside. For independent-minded Americans it was bitter medicine, and many in government and private life are happy to be free of it.

On the Arab side there is deep disappointment that the U.S. courtship has degenerated to what is called "mutual indifference" by Mazher A. Hameed, a Saudi specialist in U.S.-Arab security relations based in Washington. "Today there is absolutely nothing in the pipeline of the relationship to the United States that has any value to the Arab Gulf," Hameed said. While gulf oil producers are weighing their security needs, he added, "the United States is saying, 'Count us out. We can't do very much right now.' "

Under the pressure of falling prices, the relatively rich oil-producing nations of the gulf have lost their dominance over the Organization of Petroleum Exporting Countries (OPEC) cartel, which is now crumbling before their eyes. The collapse of unity among producers amounts to another advantage for consumers seeking to avoid dependence on any individual or group of united suppliers.

In the new atmosphere created by tumbling oil prices, the concerns of the 1970s get little attention. But this week, State Department spokesman Bernard Kalb announced U.S. concern about an escalation in the all-but-forgotten war between Iran and Iraq now 5 1/2 years old. Any expansion of the war to nearby oil-producing states in the Persian Gulf region "would be a threat to U.S. interests" Kalb said, in an echo of the energy crisis that has lost its urgency as the supply of oil has outstripped demand and prices have tumbled.