Human Rights Watch calls on one side in the Syrian conflict to stop assisting its ally. As for the US, HRW does not mind the US-German-French-Saudi-Qatari-UAE-Turkish support for the rebels

"In the wake of the Syrian government’s alleged chemical attack on its own people, it’s worth asking whether Tehran has any “red lines” when it comes to its unconditional support of President Bashar al-Assad’s government. More than 100,000 Syrians have died during the two-and-a-half-year conflict. Large numbers of civilians have been killed not by chemical weapons, but by bombs and bullets – many of which are provided by Tehran and Moscow and used by the Syrian government or pro-government forces. It is well past time for Iran’s leaders to face the facts and stop providing military assistance to a brutal government for which “red lines” clearly mean nothing. Anything less is hypocrisy at best, if not criminal complicity." (thanks Basim)