The UN Security Council's unanimous support of a peace process for Syria that is set to begin next month with government-opposition talks and a cease-fire represents its strongest gesture yet in support of a solution to the civil war, the Associated Press reports.

The council's adoption of a resolution Friday, December 18 backing the plan comes amid world powers' growing sense that the top priority in Syria should be the defeat of the Islamic State group, which has exploited the country's years of chaos and created a base from which it promotes deadly attacks abroad.

U.S. Secretary of State John Kerry told reporters that the world is going to see in the next few months whether the peace process actually takes hold. He urged key powers, including top Syria allies Russia and Iran, to match their words with actions.

"Within a month or so, two months, decisions are going to have to start to be made about the devolution of some power" and the creation of a transitional body agreed to by Syria's government and opposition with full executive power, Kerry said.

But the resolution makes no mention of the most contentious issue, the future role of Syrian President Bashar al-Assad. Kerry rejected the idea that Friday's vote and discussions put off tough decisions on that issue.

The United States, its European allies, Saudi Arabia and other Arab nations have insisted that Assad must go, though Kerry said "everyone" has by now realized that demanding Assad's departure up front in the process was "in fact, prolonging the war."

Kerry said "sharp differences" remain on Assad and stressed that "Assad has lost the ability ... to unite the country."