Authoritarian regimes in Middle East have never felt so vulnerable

The stunning display of American military might that toppled Saddam Hussein has not only achieved "regime change" in Iraq. It is sending shock waves through the Middle East and will transform the regional balance of power, albeit in ways that may not be apparent.

Officially, the goal of the United States could not be more ambitious: the creation of a democratic Iraq and the emergence of that country as a model for democracy in a part of the world that, hitherto, has been resistant to it.

That vision, dear to the "idealist" wing of the Washington neo-conservatives – led by Paul Wolfowitz, the deputy defence secretary – may prove unrealisable, in Iraq and beyond. But some entrenched authoritarian regimes in the Middle East have probably never felt so vulnerable. Foremost is Syria, which this weekend will receive a harsh lecture from Colin Powell, the US Secretary of State.

The fall of Saddam's Iraq has left Syria diplomatically isolated and economically vulnerable, now that its tap of cheap Iraqi oil has been closed.

As General Powell will make clear, Damascus is susceptible to pressure to cease its support for terrorist groups such as Hizbollah, which operates against Israel through Syria's client state of Lebanon.

The prospect of a direct US attack against Syria, raised in thinly-veiled form by Donald Rumsfeld, the Defence Secretary, during the closing stages of the Iraqi campaign, may have receded. But Syria's President, Bashar al-Assad, is on notice. As Ari Fleischer, the White House spokesman, said yesterday, Syria had to "reconsider its role in the world".

President Assad will need no reminding that, as was the case in Saddam's Baghdad, his iron-fisted rule is imposed by a minority group, in Syria's case the Alawites, accounting for 12 per cent of the population. He will wonder: if Iraq has been "liberated", might not the US work behind the scenes for the "liberation" of Syria, if Damascus does not co-operate in the search for Middle East peace?

Another loser is Iran, a fellow member with Iraq in George Bush's "axis of evil".

Iran has had a ringside view of America's overwhelmingly powerful armed forces in action. President Bush says he plans no further wars in the region. But the fact that he felt it necessary to issue such a denial will lead to second thoughts in Tehran about its sponsorship of Hizbollah.

Indeed, the landscape looks much less promising for extremist groups in general. No longer will Saddam's bounty be available to the families of suicide bombers. True, the "Arab street" is resentful, and the war may fuel recruitment by al-Qa'ida, but their financial support has surely been diminished as a result of this war.

Yet the tremors will extend into countries counted among American allies. Saudi Arabia has already learnt that US troops will be withdrawn from its territory. This may improve the longer-term prospects of the monarchy, but not necessarily the short-term ones, in a repressive and corrupt country where Islamic radicalism is one of the few alternative political outlets.

The same goes for Egypt, the second largest recipient of US foreign aid after Israel. Before the war, its President, Hosni Mubarak, warned that a conflict in Iraq could destabilise the entire region – including, he might have added, his own country, which is facing grim economic and social problems. In lesser measure, the same goes for Jordan as well, though unlike his father in the Gulf War in 1991, King Abdullah II has broadly aligned Amman with the US.

But events will be conditioned by what happens between the Israelis and Palestinians. If the US uses its power to bring about a settlement that leads to a viable, genuine Palestinian state, many of the tensions will ease. With no settlement, the squeeze on moderate Arab states, caught between expected backing for the US and the pro-Palestinian mood among their people, could become intolerable.