With ISIS, Syria's universal enemy, largely defeated last year, international powers have begun to turn on each other in 2018.
The Syrian military has forced the insurgents of eastern Ghouta to either surrender or leave, but pro-Assad forces expected a fight with ISIS in the south.
Russia, Iran and Syria suspect that the U.S. is trying to split Syria and the region as a whole in order to take advantage of the unrest.
Russia, Iran, and Turkey plan to divide the spoils of Syria's eventual reconstruction, experts say.
Turkey and its insurgent allies are sweeping through Kurdish territory and risking an international conflict with the U.S., France, Syria and Iraq.
The U.S. and Russia have both contributed to the fight against ISIS, but their goals for postwar Syria differ.
Iraq and Syria declared victory over ISIS in late 2017, but the U.S. and Turkey have resisted calls to withdraw their forces.
The new law is again stoking fears of new restrictions on freedom of expression.
After defeating ISIS, Iraq and Syria have called for a complete withdrawal of Turkish forces battling Kurds in both countries.
Andrew Brunson, a U.S. citizen from North Carolina, was arrested in Turkey in the wake of the 2016 attempted coup against Turkish President Recep Tayyip Erdogan.
The U.S., Iran and Syria all have complicated relationships with Turkey, which sees the Syrian civil war as an opportunity to tackle Kurdish groups.
They had hoped to sell the material to an unknown buyer.
Tensions between local and international actors have led to nonstop violence and more than 500,000 deaths, but there are some signs of rehabilitation.
Less than two weeks after Russian President Vladimir Putin showed off advanced weapons, his officials are warning the U.S. against action in Syria.
With fewer local allies, the U.S. may no longer be able to fight ISIS on the ground in Iraq or Syria.
The U.S. has threatened to impose sanctions on Turkey in a bid to stop it buying the S-400 from Russia.
South Koreans living in Turkey first flagged the video after the PyeongChang Winter Olympics.
Saudi Arabia's crown prince reportedly accused Turkey of wanting a new caliphate and Iran of exporting revolution.
The Interior Ministry of Turkey said security forces and the military arrested up to 4,698 in the past week.
The shifting dynamics of Syria's seven-year war have pitted the U.S. against NATO ally Turkey as well as Russia and Iran.
The Kurdish majority of the Pentagon-created Syrian Democratic Forces are leaving the U.S. battle against ISIS to fight a Turkish invasion.
Turkey's hunt for a Kurdish leader has sparked a diplomatic crisis with a European ally.
The axis of Russia, Iran and Syria faced attacks from Turkey in Afrin and Western pressure to cease bombing rebels in eastern Ghouta.
One leading Russian senator said, "It would be good if the Americans, along with us, took part in liberating eastern Ghouta from the terrorists."