As to Syria, as was shown during the Clinton era vis a vis Saddam, and even the Tomahawk launch on Al Q's ops in Afghanistan, 1998, lobbing Tomahawks doesn't tend to solve your problem. It just makes a bunch of stuff blow up. While that by itself isn't a bad thing, it doesn't do what putting bayonets and boots on the objective does.
The Marines and the Army tend to agree on the old adage:
"You can bomb and strafe all day, but until you put boots on the objective, it isn't yours."
Of course the Marines and Army agree on that. They would - it doesn't mean it's always the appropriate action. Have we already discarded the Libya example? Blow stuff up from a safe distance until such time as the indigenous boots on the ground can put themselves on the objective. Much cheaper in blood from our point of view - and the treasure all gets recycled into the economy through the missile manufacturers. Afghanistan was going pretty well with just a few western SF on the ground; it was dumping in all the other "boots on the ground" that sent it pear-shaped.