Just about everyone who's paying attention agrees that the prospects for a negotiated settlement in Syria are dismal, a consensus that’s both depressing and an understatement. Depressing because the killing continues without letup. Between 10,000 and 17,000 people are estimated to have been killed so far, about 200,000 have fled to neighbouring countries and more than 1 million are internal refugees. An understatement because the only real peace plan, that of Kofi Annan, the former United Nations secretary-general and now UN special envoy to Syria, is in tatters because of incompatible preconditions attached by Bashar Assad’s Alawite-minority government and the armed opposition.

There are two reasons for the continued fighting. First, although the insurgents have turned a war once confined to the countryside and to Sunni towns such as Hama and Homs into one that threatens the regime’s hold on the nation’s two largest cities – Damascus, the capital, and Aleppo, the commercial hub – the ruling elite is not giving up. And the opposition, now better armed, more experienced and with increasing external support, thinks the fall of the House of Assad, which has lasted for more than four decades, is imminent.

The other reason the guns keeping blazing is that the major powers – the United States, China and Russia – are talking past each other and trading vitriol instead of working in concert. Washington alleges that the key to a political settlement is Assad’s departure. It has used sanctions in an effort to achieve that end and, along with its allies, pushed (unsuccessfully) for UN-mandated economic penalties. US leaders have excoriated China, and even more strongly Russia, for refusing to join the effort and for using their Security Council vetoes to save Assad.

China and Russia charge that it’s one-sided to press Assad to stop his war and to resign, and that the opposition must cease fighting as well, without preconditions. Beijing and Moscow believe that the US and its partners have hastily embraced a disparate insurgency without ascertaining what it stands for and whether it is united about Syria’s future. They believe that the triumph of a fractious insurgency would only prolong the violence.

Because China and Russia face upheavals in their Muslim regions, both worry that an Islamic regime could eventually replace Assad.

China and Russia, having abstained on, and thus enabled, a Security Council resolution on Libya that was ostensibly crafted to establish a no-fly zone to safeguard civilians but morphed into regime change, are determined to not allow that to happen in Syria.

Nevertheless, the United States, China and Russia do have common interests that could be pursued co-operatively, including the following:

• Preventing a Lebanese-style sectarian war in post-Assad Syria.

• Ensuring that Syria does not turn into a base for Al Qaeda or its affiliates, something that’s occurred in Mali and seems to be happening in Iraq.

• Engaging the opposition so that if the government that follows Assad has a strong Islamic orientation, it is inclusive, democratic and respectful of the rights of religious minorities and women.

• Securing Syria’s chemical weapons so they don’t fall into the hands of terrorists groups in the event that the regime disintegrates.

• Keeping a civil war, which is already internationalised given the external assistance that the opposition is receiving, from becoming a full-blown regional war that Iran, Lebanon-based Hezbollah, Turkey and Iraq are sucked into.

• Planning for an international effort to rebuild a shattered Syria so that it does not descend into long-term poverty and instability.

There may be other shared interests, but these can serve as the foundation for behind-the-scenes diplomacy to make things in Syria less bad than they are now.

As things stand, Washington has abandoned a UN solution after China and Russia last week vetoed the third Security Council resolution on Syria. The US is now focusing on toppling Assad. But that could take a long time, and many more people could be killed in the meantime. China and Russia increasingly understand that Assad’s regime is a lost cause, but they are unwilling to abandon it. Their problem is that they will have to recalculate or be shut out of the postwar settlement.

It is true that even under the best of conditions, the prospects are bleak that a co-ordinated major-power strategy can engineer the voluntary transfer of power from Assad to a transitional government, pending elections. Yet this much is certain: If China, Russia and the United States don’t try, the chances will be zero. That won’t be good for Syrians, or for them.