The nationwide cease-fire is to begin at midnight local time. Russia and Turkey will act as guarantors. The agreement does not include areas under the control of ISIS.
A Russian military jet crashed into the Black Sea on Sunday morning with 92 people on board. Officials say they do not consider terrorism a likely cause of the crash.
Officials in Russia say they do not consider terrorism to be a likely cause of the crash on Sunday morning. The plane crashed shortly after takeoff; all 92 people on board are believed to have died.
During his annual news conference, Russia's leader also addressed accusations of Kremlin meddling in the U.S. election by saying Democrats "are trying to blame all their failures on external factors."
Talks in Moscow between Russia, Turkey and Iran on Syria's future went ahead despite the assassination in Ankara of Russia's top diplomat. Moscow laid blame for the killing farther afield.
Turkey identified the gunman as Mevlut Mert Altintas, a 22-year-old riot police officer who shouted, "Don't forget Aleppo!" Seven people were arrested Tuesday, and one was later released.
Andrei Karlov was shot Monday evening as he delivered a speech at an exhibition opening in Turkey's capital city. A Turkish minister identified the gunman as a 22-year-old Turkish riot police officer.
President Obama says there's a need to develop new rules as countries increasingly spy on each other in cyberspace. The U.S. is particularly vulnerable because so much of the economy is digitized.