The attack, though mostly symbolic, was a modestly good move by Trump since it backs him out of the non-interventionist corner he painted himself into. He will now be more credible when speaking of red lines. The issues regarding the War Resolution Act of 1973 are irrelevant given the historical precedent of ignoring the letter (if not the spirit) of that legislation.
No, it was a terrible move because it put us in a less secure position in the region. All of the agreements about not shooting down each others' aircraft are out the window. The deescalation hotline is dead. The Russians are putting in more advanced SAM batteries. We didn't even hit the building where they kept the sarin. We didn't disable the runway. It was worse than useless. It was actively bad for American interests in the region. Going forward, we're going to be dealing with a major area-denial situation that previously didn't exist. Good luck trying to keep all those 5th gen stealth fighters on station when the tankers can't get close enough.
It was a fucking stupid move. Although, I can sort of understand it from the DoD's perspective. The "wait for the right opportunity" option was probably off the table per Trump. A Tomahawk strike was probably the least bad option, and looks good on TV.
The Russians were given advance notice of the attack and Putin embraces realpolitik
wholeheartedly so that he knows to ignore this operation (and because we know this about Putin [and he knows that we know], the attack likely calculated all of this in the background; Trump might be a moron but Mattis and McMaster are not).
My point wasn't arguing about the US's (vaguely defined) interests in the area nor was it about the efficacy of this attack; rather, the critical point was to redefine Trump's dovish foreign policy tilt in favor of one where military action is credible. I suspect had Hilary won, al-Assad would not have used chemical weapons (assuming the motivation was to test Trump's resolve rather than an unauthorized use not centrally coordinated by al-Assad) because of Hillary's more hawkish stance.
Secondly, Trump practically had to do something like this after talking about red lines
. It may have been a sloppy thoughtless mistake to brashly speak the way he did about the situation in Syria, but once he did, not following through with some action would make Trump appear extremely weak to the detriment of US foreign policy in general.
Which brings me to the last point: one can't take this Syria mission a la carte
while ignoring its impact on other US objectives around the world. This attack gives the US more sabre-rattling credibility in "negotiating" other hot-spots, like North Korea.