A PARTIAL cease-fire in Syria, following intense and contentious negotiations between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov, brought a bit of respite to Syria’s long-suffering populace during the recent Eid al-Adha holiday. But, within days of its going into effect, the deal began to unravel, and the chances of it providing a way forward to end Syria’s agony appeared remote.Even on paper, the Lavrov-Kerry deal sounded utopian: The Syrian air force was required to cease all bombings of rebel positions, and the Syrian authorities would permit convoys waiting in Turkey to deliver vital humanitarian aid to hundreds of thousands of civilians in the rebel-held portion of Aleppo; Russia would limit its own bombings to Jabhat Fatah al-Sham (the rebranded al-Qaida affiliate, Jabhat al-Nusra) and Islamic State targets; other rebel groups would be required to distance themselves from the jihadis; as the cease-fire took hold and hostilities diminished, the US and Russia would begin joint planning against Islamic State and Jabhat al-Sham (to the consternation of the Pentagon); and UN-mediated efforts to advance a political process to bring an end to the war would resume as soon as possible.By the end of the first weekend of the deal, US air strikes intended for Islamic State forces had mistakenly killed scores of Syrian government troops, causing outrage and accusations of bad faith in Moscow and Damascus; Syrian barrel bombs had targeted a number of rebel areas; and the aid for Aleppo remained blocked. And as the second week of the cease-fire period began, rebel-held areas of Aleppo were bombarded by government forces and a UN-organized aid convoy to a rebel held area outside of Aleppo was struck by Syrian war planes, killing twelve persons and destroying 18 food-laden trucks.Five and a half years of war in Syria has resulted in 300,000 fatalities, massive destruction of Syria’s cities and towns, and the uprooting of more than half of the country’s prewar population of 25 million people, with all the attendant and ongoing consequences for neighboring countries, Europe and the international community as a whole.The central government controls less than half of the country’s national territory, but neither it nor the myriad and fractious opposition groups possess the capability of achieving victory.During its first quarter-century of independence (1945-1970), Syria was a weak state and, thus, a crucial geopolitical arena for the ambitions of rival regional and great powers. This “struggle for Syria” ended with the advent of Hafez Assad to power. Over the next 30 years, Assad managed to turn Syria into a middle-level regional power that projected power outward as opposed to being acted upon. His son Bashar confidently and cockily sought to build on his father’s legacy.But all that is now gone, as Syria has again become the battlefield for competing geopolitical, ideological, ethno-national and communal- tribal visions and interests. For Bashar, the inner circle of his regime and the Alawite community on which it is based, the conflict has always been a zero sum game. Thanks primarily to military and economic support from his external patrons – Russia and Iran, along with thousands of Lebanese Hezbollah fighters – he has managed to survive.His removal from power is no longer a Turkish and Western precondition for a transitional political process. The recent firing of Syrian anti-aircraft missiles at Israeli warplanes indicated Bashar’s increased confidence.As for Turkey, Recep Tayyip Erdoğan’s initial hopes for a post-Assad Sunni-dominated Syria under Turkey’s patronage had long fallen by the wayside. Turkey’s primary concern these days is not Assad’s fate or Islamic State, but the assertive Syrian Kurds.Its main goal is preventing Syrian Kurdish control of a contiguous belt of territory opposite its southern border across from restive Turkish Kurdistan. Turkey’s anti-Kurdish actions have caused endless headaches in Washington, which is counting on Syrian Kurdish forces to help spearhead the fight against Islamic State.The conflict in Syria must also be understood through the complementary lenses of sectarianism (Shi’ite vs. Sunni) and regional geopolitics (Iran vs. the Sunni Arab bloc, led by Saudi Arabia).Shi’ite Iran’s regional ascendance, particularly since the 2003 Iraq war, has been of overriding concern for the oil-producing Sunni Gulf monarchies and periodic US reassurances to their nervous allies have been unconvincing. Hence, the Syrian uprising against Bashar’s regime – Iran’s closest regional ally for more than three decades – seemed to provide an ideal opportunity to change the regional balance of power.In what was reminiscent of the war in Afghanistan in the 1980s, Gulf money and weapons poured into Syria to fund opposition militias.As in Afghanistan, they have proven to be a double-edged sword. Stalemated conflicts are sometimes ripe for resolution, or at least substantial de-escalation. The Syrian war, however, is not, and the agony is likely to continue indefinitely. The author is a professor in the Department of Middle Eastern and African History, and Senior Research Fellow at the Moshe Dayan Center for Middle Eastern and African Studies, Tel Aviv University.