A child rides his bike past buildings destroyed in Syria’s civil war, in Douma, near Damascus, 1st March 2016 ©NurPhoto/SIPA USA/PA Images

The shocking images coming from Aleppo in recent weeks are a stark reminder that there still seems no end in sight for Syria’s brutal civil war, now well into its fifth year. Over 500,000 have been killed and five million are refugees. What began as a largely peaceful revolt against Bashar al-Assad’s dictatorship has now morphed into a brutal, multi-facetted conflict with heavy international involvement. Might international players hold the key to the war’s overdue end?

International interventions in civil wars are nothing new and political scientists have long sought to analyse their impact. Several studies show that while heavy intervention on one side can bring about a swift end to a civil war, “balanced interventions,” when multiple actors intervene on each side, prolong conflict by creating a stalemate. Syria is a clear case of such a balanced intervention. From the beginning of the war Assad’s allies, Russia and Iran, have been willing to commit more to helping the regime than its foreign enemies—Saudi Arabia, Qatar, Turkey and the west—have to toppling it. By providing weapons, money, diplomatic support and more recently troops and airpower, Moscow and Tehran have ensured the regime’s medium-term survival. However, they have not solved Assad’s chronic manpower shortage, making it difficult for the regime to reconquer and hold host…

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