I don't support the U.S. being involved with regime change in Syria, joining a side to win that civil war, engaging in nation building, or even being remotely responsible for the fate of that nation. We aren't the ones who can determine the future of Syria, nor are we responsible for doing so, regardless of how that civil war plays out. Those are the problems for the citizens of Syria, and not the United States.
That said, I believe there absolutely needs to be a harsh response to anyone utilizing chemical, biological, and nuclear weaponry. If we tolerate Assad using chemical weapons, we'll tolerate the next butcher doing the same. And the next one, and the next one.
To me, this is a significantly different situation than Iraq, where we invaded someone we accused of possessing weapons of mass destruction. In this case, we would be hitting someone who is actively using them right now. To me, that's a huge difference and is in the interest in our national security to put the ever living fear of God in any nation that would ever think to use weapons of mass destruction.
Sadly, we've seen that issuing sanctions, making UN resolutions, proposing talks & roundtables, moralizing, or waving our fingers at the combatants of this conflict has had absolutely no impact on Syria. Frankly, factions that are desperately fighting an existential conflict to survive don't care about resolutions or sanctions. The only penalty that Assad will ever feel is hitting his military assets, which he needs in order to survive this civil war with his head intact.
So, I'm fine with punishing Assad with cruise missile strikes, drone attacks, and extremely targeted surgical strikes based on intelligence assets we already have in Syria. We won't wipe out every WMD they posses, but we'll certainly have an impact on his military infrastructure and ability to win his civil war.
While I have some serious reservations when it comes us using special forces in Syria, I'd understand the need to keep that on the table. What I'm opposed to is the type of extensive combat/occupation forces that we always use when we engage in pointless nation building exercises. We should never be patrolling the streets of Damascus or trying to install our version of order over there.
In my opinion, the goal in hitting Assad's military assets shouldn't be done to "win the civil war", but to damage anyone who utilizes actual weapons of mass destruction. With or without the blessings of the UN (which will never materialize thanks to Russia or China), whatever happens to Syria in the long-term future, Assad should be made to regret ever having used weapons of mass destruction, and make future warmongers use their WMDs for saber rattling, and not for actual use on the battlefield.
I'm sure I'm in the minority when it comes to this opinion, but I felt it was something I should state out loud. As usual, YMMV.