One doesn’t have to know the social, cultural, or political history of Syria to take a position against foreign military intervention, including by the US. The politics of any country are extremely complex internally & including its relations with other countries & with international power politics. The study of a country, in all of its dimensions, is specialized. If the millions on every continent who protested the Vietnam War waited until they had advanced degrees in Vietnamese politics, there would have been no international opposition to that war whilst the US was raining down napalm & bombs. The same is true of Afghanistan, Iraq, Yemen, Libya, Somalia, Syria.
What one has to understand is the character of militarism in the barbaric phase of capitalism. One has to understand the character of US militarism which is rooted in the extermination of the Native American population & proceeds from there to other colonial wars in the Pacific, the Philippines, Latin & Central America, Mexico, Africa, & Asia, culminating in WWI & WWII which were not fought over democracy but over colonial division of the world by European powers & the US. Opposing US military intervention is not some kind of unthinking reflex or knee-jerk anti-imperialism based in rhetoric or sentimentality. It is cynical & contemptuous to suggest that principled antiwar activists do not think through their opposition to every war or that they do not work tirelessly to grasp the complexities. The corruption of the current antiwar movement around the world is not rooted primarily in ignorance about Syria but in political degeneration, a rightward shift among progressives that has been going on for nearly 50 years. If you don’t understand that phenomenon, don’t talk through your ass about the ‘western left’ or conflate that rightwing degeneration with principled opposition to US & other foreign military intervention.