U.S. Secretary of State John Kerry says the United States will not rush into a deal with Russia to try to end Syria's civil war.

Kerry has been negotiating with Russian Foreign Minister Sergey Lavrov in China. They are discussing a ceasefire between Syria's government and moderate rebels, and a possible U.S.-Russian military partnership against extremist groups.

Kerry says they've worked out many technical issues but others are unresolved.

Kerry says he and Lavrov plan to meet again Monday. He says the U.S. will take the time needed to ensure the agreement has the best chance for success.

Several previous U.S.-Russia deals on Syria have failed to halt the violence.