If a species thinks itself enlightened or evolved, it must go beyond violence to use reasoned and sustainable approaches to resolving differences.
Military actions lead to one of two outcomes - perpetual war between peoples whose antipathy grows stronger every day (ex. Israel v Palestine); or absolute destruction of one side combined with generational investment to hopefully forge peace (ex. Allies v Axis in WWII, and the resulting European Union).
Violence is a terrible answer, but if one is to use that tactic, then one must go in prepared to annihilate the other side, and then invest for decades to help create a new society. Surgical strikes, and limited engagements have proven pointless, and invariably lead to more violence.
If President Obama (or the UN or whomever) is seeking to intervene in Syria, they must either personally participate in mediating an accord between all parties, where peaceful coexistence is the outcome (unlikely); or they must eradicate all the violent elements, and prepare to spend the next several decades forging a new society (unpalatable).
There is another option. The West can urge the governments of surrounding Arab states step in. The Arab nations and Muslims in general have been under siege for years. "External" interventions have exacerbated both the internal situation, and their relationship with the rest of the world. They must come together to make their communities and peoples find lasting peace. It can not come from without.
If the majority of peaceful Arabs and Muslims in the world are not horrified by the violent acts of a malevolent minority, then the majority has a much bigger problem - their own similarly evil nature.
I don't believe this is the case, I think they are complacent because the West has always swooped in.
It is time for America and her cohorts to recognize their impotence; to suppress their compulsion to intervene; and to allow the Arabs and Muslims the room to forge their own tomorrow.
Lasting peace can not be imposed, it must be chosen.