5-mile radius
"Anyone within a 5-mile radius of Assad should evacuate."
That's the statement I would issue if everything could be verified. If the concept of policing is good, and the policing is good, then yes, I would want the world to have policemen.
However, if this geopolitical jockeying for the economic power of the few, then of course it is not morally justified.
I think the U.S. has a bunch of secret weapons like neutron bombs, biological and chemical weapons, insect drones, lasers, electromagnetic pulse, stealth armor, micro-cameras and tracking. If it is morally justified and verified, this is the time to use one of them.
I would not want to take innocent lives, as Obama has shown he is willing to do with drones in Pakistan. Any action should be targeted toward whoever decided to use chemical weapons. And other weapons, as far as I'm concerned.
One way to avoid the taking of life might be to announce precisely where you're going to strike, at headquarters, etc. It has to be a tough decision no matter what.