The problem is that the U.S. shouldn't be involved in the Middle East. It seems like the last administration was focusing on having Iraq able to control the situation in their own country so that America could eventually be out of there for good. The only reason I can see for an attack on Syria is that they made fools out of us with the sarin gas thing, which isn't a good reason at all. Not that the retaliatory attack on them was effective.
According to the U.N. and French investigators, the original sarin gas attack way back when was by the rebels. They not only had stores of the stuff to make sarin gas bombs (which has gone completely unnoted and unpunished), but the gas in the attack wasn't high enough quality to have been Assad's. The fact that Obama and Kerry couldn't provide any kind of reasonable proof that Assad would do such a thing is why Congress and the rest of the world wouldn't allow an attack on him. But now, after Assad, Putin, and Obama had their little agreement that Assad would hand over all of his chemical weapons, he seems to have gassed a bunch of civilians.
If the U.N. decides he deserves punishment, NATO is going to make us go in there either way, but you're right, it should be along side of NATO forces - not just the U.S. stepping up as world police and saving face.