President Donald Trump called for Arab partners to contribute more to the fight against ISIS in Syria, but Saudi backing could further complicate the war.
A number of controversial organizations already have offices in Washington. Can fighters in Syria get one too?
"There has been nobody tougher on Russia than President Donald Trump," said President Donald Trump.
With ISIS, Syria's universal enemy, largely defeated last year, international powers have begun to turn on each other in 2018.
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.
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., Iran and Syria all have complicated relationships with Turkey, which sees the Syrian civil war as an opportunity to tackle Kurdish groups.
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 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.
Forces fighting for and against the Syrian government have blamed one another for violating a short-lived truce in eastern Ghouta.
"Those who have to leave Syria are the ones who have not been permitted by the Syrian government," said one of the top advisers to Iran's supreme leader.
Iranian supreme leader Ayatollah Ali Khamenei said, "The U.S. government is the cruelest and most merciless system in the world."
"The actions of the U.S. coalition do not comply with legal norms. Beyond all doubt, it is an unprecedented act of aggression," one Russian senator said.
An account affiliated with Turkey's so-called Operation Olive Branch claimed Kurdish fighters attacked the Free Syrian Army with chlorine gas.
As a Turkey-backed offensive neared Manbij, Syria, the head of U.S. Central Command said withdrawal was "not something we are looking into."
"It is a strange incident," Turkish media analyst Nate Schenkkan told Newsweek.
Neither Russian, Syrian nor U.S. forces have moved in to stop the Turkish invasion aimed at ousting Pentagon-backed Kurds from the enclave of Afrin.
Turkey and Syrian rebels have launched a joint operation against Syrian Kurdish forces, putting the U.S. and Russia in a difficult position.
The U.S.'s highest-ranking enlisted soldier said the coalition would beat ISIS fighters to death with shovels if they didn't give up.
"The U.S. must step back from this grave mistake and not allow itself to be blackmailed by the terrorist outfit," Turkey's top diplomat said.