Neither is likely to come soon enough for the suffering Syrian people, whose casualties and the destruction of towns and cities, including irreplaceable historical sites, have become heart-wrenching.

President Assad has rebuffed the offer of asylum by British Prime Minister David Cameron as a way out of the crisis, vowing to stay in Syria until death or victory. He still counts on his formidable military firepower, and support from his minority Alawite, as well as elements of other minorities, most importantly the Christians and Druze (who together form about 20 per cent of Syria's population of 20 million) to weather the storm.

The regime's two regional allies, Iran and Hezbollah in Lebanon, remain firm in their backing as critical to their regional interests, and Moscow and Beijing appear in no mood to back away from the regime as part of their major power rivalry with the United States and its allies in the region and beyond.

The human toll of the crisis has already reached an astronomical proportion: more than 30,000 Syrians have been killed; many more thousands injured, and some 2½ million and 250,000 have become internal and external refugees respectively.

The international aid agencies, most importantly the International Committee of the Red Cross, now find it very difficult to cope with the humanitarian crisis.

Meanwhile, the opposition, which is made up of a number of political and military groups, remains very divided. Its elements range from democrats, to nationalists, to radical Islamists. Their gathering last weekend in Doha, backed by the US and Gulf Arab states, has resulted in the declaration of a loose coalition, but this may not enable them to form an effective alternative government and provide a unified political and military leadership.

The US and its allies continue to remain cautious against providing the opposition with the weapons it needs to bring down the Assad regime sooner rather than later.

As for a direct NATO intervention similar to that in Libya last year, there seems little scope for it. Neither the US nor its allies have the political will for such action; nor do they want to complicate their relationships any further with Russia and China.

The Syrian situation is also logistically highly complex.

The front-line state and NATO member capable of taking the lead in any military intervention is Turkey, but Ankara remains mindful of its lucrative trade relations with Iran, traditional differences with Russia and the Arabs' historical suspicion of Turkey as a successor to the Ottoman Empire, which once ruled most of the Arab world.

The Syrian crisis cannot now be resolved at a national level alone. It is too deeply entangled with acute regional and international complexities. Two developments are needed for a speedy resolution of the crisis. One is a US-Russian-Chinese summit, whereby these three powers could reach a common understanding about the issue, which may well necessitate trade-offs in relation to their differences beyond the Syrian crisis.

Another is for the United States and Iran to settle their disputes and move towards a rapprochement. While the difficulty of the task cannot be underestimated, both Tehran and Washington are now better placed to move in this direction.

The tightening of sanctions by the US and its main European allies, especially against the Iranian Central Bank and oil exports, over Iran's nuclear program, has seriously undermined Iran's already fragile economic situation, largely due to its mismanagement under President Mahmoud Ahmadinejad. It has caused widespread hardship for Iranians, diminishing the popular support for the ruling clerics to an unprecedented degree.

Iran's Islamic regime can no longer afford to carry on business as usual. If it wants to maintain its power base it has to address the economic crisis and shore up its popular base.

It needs to come to terms with the US, one way or another. Some elements within the ruling clerics are willing to reach out to the US for a resolution of the nuclear dispute, but most likely in the context of also tackling a number of other differences between the two sides.

Similarly, given his re-election and new mandate, President Barack Obama has a new opportunity to show an unequivocal resolve to engage Tehran directly on a quid pro quo basis to settle the nuclear dispute and a range of other issues, including the enduring Israeli-Palestinian conflict, that have eroded the two sides' confidence in each other.

One way to resolve the nuclear dispute is through promoting a region-wide regime of arms control that includes Israel. President Obama should no longer be constrained by the US's exceptional deference to Israel and its close ties with some of the Arab regimes in the region, which have found the continuation of US-Iranian hostilities, and in the case of Israel also the Syrian conflict, in their interests.

Without such developments, the Syrian crisis can be expected to continue for some time, at a greater cost to the Syrian people and to the enduring shame of regional and international actors.

Amin Saikal is professor of political science and director of the centre for Arab and Islamic studies (the Middle East and Central Asia) at the Australian National University.