We assisted the mujadeen in Afghanistan for no other reason than to screw with the Russians. As we've had to learn for experience, Afghanistan is a country which no foreign invader has ever conquered. Russia eventually retreated but if we really wanted to screw with them, we'd have stayed out of it. I'm not claiming that anyone could foresee Bin Laden. My assertion that the effort was not worthwhile or not ideologically sound.
We are opposed to the spread of Communism. We thought we were fighting it in Vietnam. How's that domino theory working out? Russia, with the collapse of the Soviet Union, is no longer communist, allowing it's citizens some property rights and a degree of capitalism.
We have the means to stick our nose into any corner of the globe. Our military is pretty bad ass. We could have come to the aid of Tibet, we could stick our nose in Kashmir. We don't because it's not in our national interest. Neither is Syria.
The rebels claim that they have chemical weapons. Are you calling them liars? Just curious.