Cynics would suggest that Bush is looking for photo opportunities that might add some spice to his future memoirs. More generous commentators might see the tour as the continuation of an American tradition: All US presidents since Woodrow Wilson have dreamed of themselves as peacemakers and tried to help others sort out ancient disputes.

Both assessments may be true. After all, why shouldn't Bush look for a photo opportunity, and why shouldn't he try his luck at peacemaking? But those explanations are inadequate.

First off, the greater Middle East is no longer a distant region whose importance to the United States stems from its oil reserves and strategic location in the context of big-power rivalries. Over the last three decades, US dependence on Middle East oil has dropped steadily, even as US imports of crude have almost doubled. As for geostrategic factors, the Cold War's end spelled the finish of the Middle East as a big prize in the race between the Free World and the Soviet bloc.

Instead, the Middle East has emerged as the chief source of threats to US national security in the context of a new global struggle between the established order and its challengers, who often act in the name of this or that version of Islam.

Successive US administrations failed to see this radical transformation when it began in the '70s. Even the storming of the US embassy in Tehran and the seizing of American diplomats as hostages failed to convince Washington that something important was going on in the Mideast. It took the 9/11 attacks to shake America out of its illusions about the region.

Since President Franklin Roosevelt, US Middle East policy had aimed at preserving the status quo. Each time America intervened in the region - from the Marines landing in Lebanon and Jordan in the '50s to the expulsion of Saddam Hussein's armies from occupied Kuwait - Washington sought to maintain as much of the status quo as possible.

That policy's failure - illustrated by the emergence of pro-Soviet Arab regimes in the '50s and the '60s, the Communist seizure of power in Afghanistan in 1977 and the Khomeinist revolution in Iran in 1979 - didn't persuade Washington that a different analysis might be required. But Bush realized post-9/11 that it was the very status quo that America had helped preserve that had produced its deadliest foes. He became the first US president to adopt an anti -status quo, not to say revolutionary, posture toward the Middle East.

Bush backed his words with deeds by taking military action to remove two of the region's most vicious regimes in Afghanistan and Iraq. He also exerted pressure on other countries, including some allies, to change aspects of their domestic and/or foreign policies.

The upshot: The status quo has shattered. Yet (even leaving aside the peoples of Afghanistan and Iraq, who've had a chance to taste freedom from tyranny) America hasn't been the sole beneficiary.

Indeed, the prime beneficiary has been the Islamic Republic in Iran. In 2001, it was in a pincer between the Taliban regime in Kabul and the Ba'athist regime in Baghdad. The Afghan mullahs challenged the Iranian mullahs on religious grounds; the Ba'athists tried to mobilize pan-Arab nationalism against Khomeinism. Those regimes' fall has enabled the Khomeinists to revive their ambitions of regional supremacy as never before.

Other beneficiaries include Russia, India, China and Uzbekistan - who were all mired in deadly struggles against armed Islamists. The Taliban's fall and the destruction of al Qaeda's Afghan network have led to the gradual demise of terrorist groups in Chechnya, Kashmir, Xingjian and the Ferghana Valley.

* Freed from the Chechnyan albatross, Vladimir Putin's Russia has revived its big-power ambitions in Central Asia and the Middle East.

* The end of the Muslim revolt in Xingjian has enabled China not only to develop that oil-rich region, but also to attract massive Arab investment.

* India has freed itself of the cross it had to bear in Kashmir, letting it cut defense spending for the first time in half a century and focus on economic development.

* With no more mujahedin coming from Afghanistan, Uzbek President Islam Karimov has been able to restore his control over the Ferghana for the first time since 1990.

Arab states from Algeria to Yemen to Egypt, have also benefited from the fact that Afghanistan and Iraq have become magnets for terrorists who'd otherwise have targeted them. Europe and Japan gained, too, if only from the receding of the Saddamite and al Qaeda threats to a region that provides 60 percent of their oil imports.

The problem is that, while the old status quo has fallen, a new one has yet to take shape. The struggle against the enemies of new Afghanistan and Iraq may continue for many more years. Under a new administration, America may balk at the effort required to shape a new status quo. A US withdrawal before a new balance of power is in place could leave Iran and Russia the arbiters of the region's future. Both have made no secret of their ambitions to build alliances to challenge what they see as US domination.

The State Department may have designed Bush's final tour of the region as a signal that America is satisfied with the half-built Mideast status quo. This is why the focus is put on the Israel-Palestine conflict - which, its intrinsic importance notwithstanding, is of little consequence in the broader struggle for a new Middle East.

The president's tour can acquire a positive meaning only if it is used to shape a new alliance for reform, progress and democratization as the chief guarantor of Middle East peace and security. Such an alliance would challenge the hegemonic ambitions of both the Islamic Republic and Russia.

Under Bush, America has helped change the Middle East. It would be odd, to say the least, if America's principal adversaries end up as the chief beneficiaries of that change.