With conflicting interests and competing global powers, the international community remains at an impasse over Syria's six-year conflict.
On Friday morning local time, the US military struck a Syrian airbase in response to a chemical weapons attack, bringing mixed reaction from global players. Some lauded the action as long overdue, while others condemned it as "an aggression."
Here's a look at the key countries involved in Syria, their reactions to the airstrike and their stakes in the conflict.
Involvement: Since 2014, the US has headed an international coalition conducting airstrikes on ISIS targets in Syria. Under former President Barack Obama's administration, the US launched a military campaign against ISIS in both Iraq and Syria. Since then, President Donald Trump's administration continued Obama's bombing campaign against ISIS.
But the airstrikes marked the first direct military action the US has taken against the regime of Syrian President Bashar al-Assad.
Desired outcome: The Obama administration had said that Assad must go. There are questions whether the Trump administration's approach to Syria will shift from his predecessor. A week ago, US Secretary of State Rex Tillerson said the "longer-term status of President Assad will be decided by the Syrian people." It remains to be seen how the airstrikes affect the Trump administration's policy on Syria.
Reaction: Opposes airstrike
Russian President Vladimir Putin regards the US attacks on Syria as "an aggression against a sovereign state in violation of the norms of international law, and under a trumped-up pretext at that," Kremlin spokesman Dmitry Peskov was quoted in Russian state-run news agency Sputnik.
This could bring new strain in the US-Russia relationship.
"Co-operation between the Russian and US militaries may be shut down after the US strike," said Viktor Ozerov, head of the defense committee in the Federation Council to Russian state news agency RIA.
He said Russia will demand an urgent UN Security Council meeting after the US airstrike, calling it "an act of aggression against a UN member."