Jackson Diehl in the Washington Post offers a concise repetition of the standard propaganda narrative of U.S. policy towards Syria:

The crisis in Egypt has been distracting attention from the civil war in Syria, where Obama’s stubborn refusal to act has facilitated the emergence of the largest and potentially most dangerous incarnation of al-Qaeda since pre-2001 Afghanistan.

According to this, the official narrative, it is the U.S.'s inaction that has led to this threat emerging. Thus, by this account, what the U.S. should do now is to act, which invariably means backing the rebels, including by directly arming them.

The truth (as I've pointed out again and again and again and again and again and again and again and again and again) is that what "has facilitated the emergence of the largest and potentially most dangerous incarnation of al-Qaeda since pre-2001 Afghanistan" is the U.S.'s policy of seeking regime change in Syria by supporting the armed rebels, whose ranks include Islamic extremist groups such as the al-Qaeda-affiliated Jabhat al-Nusra and now the "Islamic State of Iraq and the Levant", including CIA coordination of the flow of arms, most of which ended up in the hands of the jihadists.

Depending on which narrative one believes, the propaganda one or the true one, one arrives at polar opposite conclusions about what the U.S. should do now. There is little hope, however, that policymakers in Washington will do anything other than continue to act according to Einstein's definition of "insanity".

Another relevant one: