In Syria’s complex war zone, with its many different warring groups, documenting exact casualty figures and determining who is responsible for which fatalities is a challenging task.
Several NGOs -- notably the Syria Network for Human Rights, the Syrian Observatory for Human Rights, Airwars, and the Violations Documentation Center -- track and cross-check casualty figures, often with the help of monitors on the ground, as well as local activist groups such as Raqqa Is Being Slaughtered Silently.
Moscow launched its air campaign on September 30, 2015, with the stated aim of targeting Islamic State (IS) militants and shoring up Russia’s ally, Syrian President Bashar al-Assad. But from the get-go, Western governments and Syrian opposition activists said Russia was primarily targeting not IS, but rather other rebel groups opposed to the regime. These have included some backed by the United States and its allies, who by the start of Russia’s intervention were one year into their own air campaign targeting IS forces in Syria and Iraq.
Six months into Russia’s air campaign, rights groups said its strikes had killed more than 1,700 civilians, amid allegations that Moscow’s planes had deliberately targeted hospitals and other civilian areas.
To be sure, strikes by the U.S.-led coalition have caused civilian deaths too -- more than 1,500 in the two years since the coalition launched its operation against IS in Iraq in August 2014 and Syria the following month, according to Airwars.
U.S. Central Command has acknowledged a total of 55 civilian fatalities.