Secretary of State John Kerry says a "provisional agreement" has been reached on a ceasefire in Syria's five-year civil war.

Kerry, who spoke Sunday alongside Jordanian Foreign Minister Nasser Judeh in Amman, Jordan, said he had spoken earlier that morning with his Russian counterpart, Sergey Lavrov, about the agreement. Now, he said, both the U.S. and Russia planned to reach out to the various sides of the conflict.

Kerry said he hoped President Barack Obama and Russian President Vladimir Putin would talk soon and that hopefully, after that, implementation could begin.

Kerry said details of a ceasefire still need to be resolved, such as enforcement.

Kerry said not every party will necessarily agree automatically, but said "There is a stark choice for everybody here."