The Syrian civil war was always a proxy war between outside military powers, but this week the proxy element became much larger and much more dangerous.
For example, today are forces are rushing to the Syrian-Turkish border to try to stop our two allies from shooting each other.

U.S. armored vehicles are deploying in areas in northern Syria along the tense border with Turkey, a few days after a Turkish airstrike that killed 20 U.S.-backed Kurdish fighters, a Syrian war monitor and Kurdish activists said Friday.
Footage posted by Syrian activists online showed a convoy of U.S. armored vehicles driving on a rural road in the village of Darbasiyah, a few hundred meters from the Turkish border. Clashes in the area were reported between Turkish and Kurdish forces Wednesday a day after the Turkish airstrike which also destroyed a Kurdish command headquarters

In other words, they are peacekeeping forces in a war zone.

"The U.S. role has now become more like a buffer force between us and the Turks on all front lines," he said. He said U.S. forces will also deploy as a separation force in areas where the Turkish-backed Syrian fighting forces and the Kurdish forces meet.
It is a message of reassurance for the Kurds and almost a "warning message" to the Turks, he said.

On the opposite side of Syria another proxy war is developing. This one has different players, with different agendas.

Syria's military said Israel struck a military installation southwest of Damascus International Airport before dawn Thursday, setting off a series of explosions and raising tensions further between the two neighbors.
Apparently seeking to interrupt weapons transfers to the Hezbollah group in Lebanon, Israel has struck inside Syria with increasing frequency in recent weeks, making the war-torn country a proxy theater for Israel's wider war with Iran.
The increasing tempo of attacks risks inflaming a highly combustible situation drawing in Israel, Syria and the Iranian-backed Hezbollah, a staunch ally of President Bashar Assad's government with thousands of fighters in Syria.

This is bad enough, however, there is another piece to this story that needs to be considered.

Malbrunot reported that on January 12, Israeli F-35s took out a Russian-made S-300 air defense system around Syrian President Bashar Assad's palace in Damascus and a Russian-made Pantsir-S1 mobile surface-to-air missile system set for delivery to Hezbollah in Lebanon.

The Syrian civil war is a massive proxy war with countless actors, all of them heavily armed and capable of taking the war outside of Syria.