In the present moment of international opportunity and peril, this is no time for scapegoating or second-guessing. The president has committed the United States to fateful action in the Mideast, and the consequences likely will be felt long into the next century. He enjoys, and deserves, the support of Americans of every political persuasion.

From the beginning of this crisis, George Bush has performed with skill and sureness of purpose. His personal dealings with world leaders, his quick and decisive response to Saddam Hussein's treacherous dead-of-the-night invasion of Kuwait, his measured address to the nation all have demonstrated presidential leadership of high order.

It's possible, given the extraordinary unanimity of world opinion and sanctions endorsed across the ideological spectrum of nations, that a new and more hopeful world order can emerge from the latest threatening actions in the Persian Gulf. If so, Bush will receive justified credit for helping to create it.

It's also possible that, out of the Mideast tumult, a new grouping of alliances could emerge and bring stability to a historically unstable region.

At the same time, there's considerable danger that Bush's line "drawn in the sand" will prove to be just that -- a line that can be erased quickly by the shifting of events.

Despite reassuring sounds of support from erstwhile enemies as well as allies, the United States stands virtually alone on the Mideast firing line. Most troubling has been the reluctance of other Arab states to join in forming a true multinational military force that could stabilize the Mideast and check the threat of further Iraqi aggression. Consequently, anti-American feelings in the Arab world are certain to intensify. Fulfillment of new international and regional opportunities will be more difficult.

Beyond this lie other troubling questions for the United States. This newest oil crisis hammers home, or ought to, how little Americans have learned from previous Mideast convulsions. U.S. dependence on imported oil has risen dramatically since the oil shocks of the 1970s, making the nation even more vulnerable to sudden disruption. As a society, Americans still live for the moment, refusing to take steps that would ensure long-term national security through achieving energy independence.

Nor have Americans learned how to assess the vicissitudes of Mideast politics and personalities. Hence, the repeated recent history of U.S. miscalculations in backing the wrong horses and having to pay heavy prices for those misjudgments.

In the 1970s, the United States routinely ignored evidence of internal trouble and possible revolution in Iran. The shah was given increasing numbers of blank checks to ensure that his regime would be, as U.S. officials liked to say then, "a bastion of strength" in the Middle East. They meant, of course, an American bastion of strength.

Even as the situation inside Iran turned violent, President Jimmy Carter continued to rely on falsely optimistic assessments. "I fully expect the shah to maintain power in Iran and for the present problems in Iran to be resolved," Carter said Dec. 12, 1978. Five weeks later, the shah fled into exile, first to Egypt, then Morocco, then Mexico. Eventually, when no other nation would accept him, the shah was granted sanctuary in Panama through Carter's personal intercession. There, he was placed under the charge of someone else on whom the United States relied, a Panamanian colonel named Manuel Antonio Noriega, then doing double duty on the payroll of the CIA and known to have close ties to Fidel Castro.

In the 1980s, when Iran became an enemy, the United States tilted toward Iraq as it fought Iran. Then, further compounding the record of official mistakes, Iraq's Saddam Hussein learned that the United States had secretly sold arms to Iran with the assistance of Iraq's ultimate foe, Israel.

The record of miscalculation continued until the moment that Kuwait was invaded. Even then, the United States was placing credence in assurances by Mideast leaders that Saddam had no invasion plans despite clear assessments by U.S. intelligence services of his aggressive aims and long-term territorial objectives.

Now, in the new decade, the United States faces the most critical Mideast test of all. It poses a familiar challenge and raises a familiar question.

The challenge: The real test of leadership is not how to handle a crisis but how to prevent one. That means learning from past lessons, then educating the public about what action is necessary. The question: Are Americans up to it?