You can't call the Syrian government a terrorist group;.
No. I am Not. I meant recognized terror groups,
Let's review
The Self proclaimed Caliphate are terrorists
AQ had infected the FSA like cancer until it more or less broke up resulting Tahrir al-Sham and they are Terrorists.
the Syrians have been backed by Hezbollah through Iran, Hezbollah are an internationally recognized terrorist group. Remember a few months back a Russian Soldier was spotted sporting a Hezbollah emblem
The Kurdish forces and the Syrian Democratic Forces fighting in syria have strong ties to the YPG is considered terrorists by Turkey. Remember a US operator was spotted wearing a YPG emblem.
Syrian opposition has ties to a number of groups including the Muslim Brotherhood and Hizb ut-Tahrir, Both Islamist supremacy groups and Muslim Brotherhood is a Recognized terror group in a number of nations.Hizb ut-Tahrir is considered a terror group by Turkey
So any party in the Syrian war can from anyones perspective be backed or backing a terror group.