While the US has spent years eagerly throwing arms at various Syrian rebel factions, those rebels have had a mixed record on the ground. As losses mount in Aleppo Province, in the face of a Syrian military offensive, they were expecting the US to bail them out, and now that they’re not, they complain of being “abandoned.”
This isn’t the rebels’ only gripe. Earlier in the war, the US was suggesting complete support for the rebels as the eventual government of Syria, and backed their refusal to negotiate. As they’ve shifted to get behind a Russian proposal for a settlement of the war and free elections, the rebels have viewed it as a “betrayal” of their goal of unconditional regime change.
While the US is still arming the rebels and giving lip service to regime change, their focus shifted to the ISIS war long ago. The Pentagon, for its part, says they have “no current plans” to intervene against Russia and Syria in the Aleppo offensive.
When the US made the decision to support the rebels, their victory seemed an inevitability. ISIS, however, has long since passed the rebels as a dominant opposition force. Clearly the US never had any intention of going to war with Russia to save rebel factions who had no real chance of winning to begin with.