To recap: The US has indeed claimed its primary aim in Syria is to “degrade and destroy” ISIS - but instead of allying with the Syrian army, which has been battling ISIS on the ground, Washington has spent years backing opposition “moderate rebel” forces who are fighting Bashar Assad’s government forces. In other words: Washington is backing the groups that are attacking the army which is best positioned to defeat ISIS. Or even more simply, Washington supports one anti-Assad group but bombs the other."It's Time to Admit Washington's Syria Policy Has Gone Completely off the Rails." By Danielle Ryan, RT, 9/19/16.
The US supports the rebel forces in pursuit of their broader goal which is Syrian regime change. As the war has dragged on, it’s become clearer that the US-backed rebel forces are not “moderate” in the sense that you or I might use the term. They have fought alongside and “intermingled” with Al-Qaeda’s official Syria affiliate Jabhat al-Nusra (which recently rebranded itself as Jabhat Fateh al-Sham). One of the major sticking points in ceasefire negotiations between the US and Russia has been the question of Washington’s ability to disentangle the so-called “moderate” rebels from the extremists. So far, no such disentanglement has taken place, demonstrating that the US has little to no control over its proxies.
H/t: Russia Insider.