Asher Susser: The unprecedented upheavals across the Middle East, from Tunis to Bahrain and Yemen, with Libya, Egypt and Jordan in between, have catapulted the region overnight into a new era of popular empowerment and possibly protracted instability.

However successful the uprisings may be in overturning the political order, it will take time before the underlying socioeconomic causes of the present instability are satisfactorily addressed.

The regimes that emerge from the convulsions, whether markedly different from their predecessors or more of the same, could very well be facing new outbursts of popular disaffection when the high hopes for rapid, if not miraculous, change are not immediately fulfilled, as is likely to be the case.

As the Sunni Arab states, many of them friendly to the US, have contracted politically and socioeconomically, and as they now sink even further into crisis, the void is being filled by the two old-new Muslim, but non-Arab, regional super-powers: Sunni Muslim, non-Arab Turkey and Shi'ite Muslim, non-Arab Iran.

This is a process that has been in the works for the past decade and more, and is now accelerating as the new disorder unfolds. Recent events have also thrown into sharp relief the steadily declining influence of the US and its allies in the region, in contrast to the assertive, self-assured ascendance of its major regional rivals headed by Iran.

The US 2003 war in Iraq paved the way for Shi'ite dominance of that country after centuries of Sunni control, thus exposing it to greater Iranian influence than at any time in the modern era. The centuries-old sectarian struggles of Lebanon have ended with a virtual knockout victory by Iran's Shi'ite Lebanese proxy, Hezbollah.

Elections in Palestine in 2006 produced a stunning victory for Hamas, now in full control of Gaza, and, although Sunni, still giving Iran yet another foothold of influence on the Mediterranean. As the US's rivals make gains at its expense, the US pursuit of what is increasingly looking like a lost cause in Afghanistan is likewise eroding its image as a great power. The pro-US, anti-Iranian alliance composed of Egypt, Saudi Arabia, Jordan and the Palestinian Authority is now reeling from shock after its decapitation with the removal of Egypt's president Mubarak, the staunchest of Iran's opponents and one of the firmest of US allies in the region. Iran is emboldened, as are its allies in the anti-US axis, Syria, Hezbollah and Hamas, just as the Arab allies of the US are apprehensive after what they see as an American abandonment of a friend in need.

The US could not, and should not, have propped up Mubarak in the recent popular upheaval, but the alacrity, derision and heavy-handedness with which it ultimately abandoned him will be remembered by friend and foe alike for many years to come. Other pro-US leaders in the region must be asking themselves these days whether the US can be trusted. Their anxieties are immediately translated into the triumphalism of their respective enemies, which does not add to the US and its regional stature.

The island of Bahrain, linked to the Saudi coast by a 25km-long causeway, was recently shaken by protests by its Shi'ite majority against the ruling Sunni minority regime. Although these were not necessarily inspired by Shi'ite Iran, the Iranians have laid claim to Bahrain for more than a century, and any change there in the Shi'ites' favour is bound to add to Iranian regional influence and to further dishearten the Saudis.

The Saudis are already concerned about potential Iranian-inspired subversion among their own Shi'ite minority, who are no less than one-third of the population in the oil-rich eastern province of the kingdom. A Shi'ite uprising there would not only unsettle the Saudi monarchy, but could send shock waves through world energy markets, the likes of which we have never seen.

Throughout the Middle East, the prevailing conventional wisdom in the capitals of the region and among the Palestinians - Fatah and Hamas alike - invariably assumes that a post-Mubarak Egypt would be a polity in which the Muslim Brotherhood would be a major power broker. Such an Egypt, if it does indeed emerge, would probably develop a foreign policy orientation quite similar to that of Turkey under its present-day, albeit moderate, Islamist government - that is, less friendly to the US, somewhat more conciliatory towards Iran and Hamas, and more expressly hostile to Israel.

The recent passage of two Iranian warships through the Suez Canal on their way to Syria, a usage of the canal not permitted by the Mubarak regime since the Iranian revolution in 1979, would seem to be a sign of the times. It is indicative of what could be expected in the future, both in terms of Egypt's posture and of Iran's capacity for regional power projection.

For the US and the Western industrialised nations, the new Middle East, with its all-important oil reserves, is fraught with uncertainty and potential instability at a time when their influence has diminished. The aftershocks of the latest eruption, at least in the short term, seem to have further deflated the posture of the US and other Western powers in the region. In the longer run, however, if the Middle East does indeed give birth to a series of Western-style liberal democracies, including pro-democracy change in Iran, the standing of the US and the West in general would improve immensely. Whether the Middle East is really going in that direction, however, time alone will tell.

Susser is a senior fellow and former director of the Moshe Dayan Centre for Middle Eastern Studies at Tel Aviv University