What began as a protest movement against President Bashar al Assad has killed more than 60,000 people, devastated the economy and left 2.5 million hungry.
Prospects of a negotiated peace have receded as the war becomes more overtly sectarian, making Western powers wary of supporting the largely Sunni Muslim rebellion.
Human Rights Watch pointed to the burning and looting of religious sites of minorities in recent months that suggested an escalation of sectarian strife.
As fighting raged throughout the country yesterday, Assad's most powerful foreign backer Russia said the war would not be resolved peacefully as long as rebels insisted on overthrowing the president.
Underscoring the damage wrought by the conflict – the longest and deadliest of the Arab Spring uprisings – the UN's Food and Agriculture Organisation said wheat and barley production in Syria had dropped to two million tonnes in 2012 from four million tonnes in normal years.
A UN assessment this month, co-ordinated with both Syria's government and the opposition, found the conflict was destroying infrastructure and irrigation systems and that insecurity and fuel shortages were making it harder for farmers to harvest crops.
Power cuts and fuel shortages have become part of daily life in the country and residents of central Damascus – which had been spared the worst fallout of the war – say basic services are breaking down, with petrol supplies running out..