Russia is considered the obstacle to ending the Syrian civil war on western terms, but it also holds the cards needed to force the regime to the bargaining table.
The best outcome of the conflict for both Russia and the West is a political solution involving a negotiated end to the fighting, on terms that might leave the regime in place with concessions to the rebels.
The only person who can deliver all of that without more bloodshed is Russian President Vladimir Putin. The West and the rebels may not like the idea of a Syria led by Bashar Assad, but their leverage at the moment isn't too strong.
Prime Minister Stephen Harper is right in saying Mr. Putin is supporting Syria's "thugs," but name-calling isn't a very useful strategy as he sits down with the Russian leader and the other members of the G8 group of nations in Northern Ireland today.
If Mr. Putin cannot be persuaded to exercise his influence in Syria on the grounds it is in Russia's self-interest to quell the conflict before it escalates, then the bloodletting will continue. At the moment, Mr. Harper's "thugs" appear to have the upper hand.
That appears to have been the motive behind the European Union's decision last month to end its arm embargo and President Barack Obama's recent decision to arm the rebels with light arms, possibly including anti-armour and anti-aircraft weapons.
The forlorn hope is that the weapons will embolden the rebels and extend the conflict while demoralizing Mr. Assad and encouraging him to seek a ceasefire.
Mr. Assad, however, is receiving considerable support from the Shiite militant group, Hezbollah, and plenty of help from Iran and Russia, which has offered to deliver sophisticated anti-aircraft weapons to Syria to deter a possible American-led intervention.
The rebels under the banner of the Syrian Free Army have had some remarkable successes in the two-year conflict, but over time their ranks have been infiltrated by al-Qaida and other Islamic groups that are traditionally hostile to the West.
Some American hawks believe they can separate the wheat from the chaff among the rebels, but the situation on the ground today is so confusing and volatile, it's questionable if an outright rebel victory would stabilize the region or further inflame the sectarian divisions.
The idea of a no-fly zone is also fraught with uncertainties and risks. It's worked in other contexts, but Syria is said to have a potent air-defence, which could make establishing an exclusion zone very expensive.
And unlike Libya, there's no guarantee it would open the gates of Damascus to the rebels. The more likely outcome of such a manoeuvre would be an escalation of the violence without degrading the will or ability of the regime to resist.
The use of chemical weapons by one or both sides has been described as the moral dividing line between intervention and non-intervention, but in the end self-interest is the ultimate benchmark for the Americans. At this point, despite 90,000 deaths and rising, America and its allies have not been convinced they can do more good than harm through all-out war, or even by imposing a no-fly zone. Their concerns are valid, but then they have the man in the room today who can make a difference.
Syria, Russia and China oppose the notion of regime change, but both Russia and China have supported a political solution to the conflict.
Mr. Putin wields considerable influence in Damascus and he can compel Assad to begin a negotiating process, while the Americans can use their influence to force the rebels into the same room. Both sides in the civil war must be made to realize there is only one way out of the cauldron, but it won't happen unless their benefactors give them no choice.
Mr. Putin is ideally situated to begin that process, or to risk the law of unintended consequences.