Russia must change its military targeting as it backs the Syrian regime, US Secretary of State John Kerry said on Saturday, as world powers seek a cessation of hostilities in the country within a week.
"To date, the vast majority of Russia's attacks have been against legitimate opposition groups," Kerry said of Moscow's air strikes in support of President Bashar al-Assad's forces.
"To adhere to the agreement it made, we think it is critical that Russia's targeting change."
Russia has supported the Assad regime against rebel forces whom it collectively labels "terrorists". The US has provided some support to the rebels and called for Assad to leave power.
Friday's agreement called for a "cessation of hostilities" within a week and for greatly increased humanitarian access, but it excludes the Islamic State group and al-Qaeda-linked jihadists.
"There's a lot of work to do before an effective cessation can commence," said Kerry, whose country together with Russia co-chairs a UN task force meant to find ways toward a durable cessation of violence.