Recorded phone calls suggest around 215 Russian mercenaries were killed by U.S. artillery and airstrikes in a battle in Syria on the night of February 7.
As forces supported by the U.S. and Russia defeat ISIS across Syria, Secretary of State Rex Tillerson seeks Moscow's help to prevent a new conflict.
After being attacked, a coalition of forces backing the Syrian government and fighting the Islamic State militant group has warned the U.S. not to cross "red lines."
Jordanian commentators, including the military's former deputy chief of staff, rejected notions that the U.S., Jordan and allies were invading Syria by land.
Syrian and Iranian concerns regarding the U.S. and Jordan's nearby military drills were heightened when U.S. troops were seen with rebels in Syria.
The U.S. and Russia will once again work together to avoid mid-air collisions in Syria after a falling out between the nations last month.
Buses full of rebels began leaving the Barzeh district of Damascus as the Syrian government announced hopes for peace between factions.
The U.S.-backed, majority-Kurd Syrian Democratic Forces and the Russia-backed Syrian military are separately threatening ISIS's final major strongholds.
Syria's Bashar al-Assad said President Donald Trump 'has no policies' of his own and he only follows U.S. plans to advance political and economic interests.
The U.S. military killed 18 fighters of the allied Syrian Democratic Forces in a friendly fire incident in northern Syria.
The Kinetic Energy Projectile launches a tungsten-based missile at Mach 3 that delivers a "devastating" load of hot metal fragments.
Putin claims to have evidence that the rebels are planning chemical attacks that will be pinned on the Syrian regime.
Russia bolstered its support for Syrian President Bashar al-Assad in the face of U.S. military action.
Syria's war, now in its seventh year, has killed hundreds of thousands and drawn local and international forces into a deadly contest for power.
"American policy is based on creating chaos in different parts of the world and creating conflicts among states. This is not new," Syria's President Bashar al-Assad said.
Turkish President Recep Tayyip Erdogan said "Operation Euphrates Shield" was over, but Ankara had "good surprises" in store for the Islamic State group and Kurdish militants in Syria and Turkey.
Ryan Lock, 20, died in December 2016 during a battle for the ISIS stronghold of Raqqa in Syria.