On the one hand, this seemed like a reasonable proportional response to the use of chemical weapons by Assad on his citizens. It also seems like Trump listened to his advisors and picked one of the most conservative responses he could, that's not what most of critics would have expected. On the other hand, it raises a lot more questions for me than it does answers.
First, while there is now evidence that sarin gas was used on civilians (some of the victims were children so they're certainly civilians), it's not clear who launched the attack. I believe that Assad did it, but I think some proof is required, particularly from an administration that has bullshitted us on virtually everything.
Second, it raises a long standing question. Even if Assad launched this attack, it's not clear that the US had any legal right to strike Syria in this way. My understanding is that under international law the only valid reasons are self-defense (which doesn't apply) or with Security Council permission (which wasn't asked for). This was a violation of chemical weapons treaties, but they don't authorize military force for violations. Under US law Trump also has no authority to strike Syrian forces. The 2001 AUMF against al-Qaeda has been used for years to cover strikes against ISIS and even that is on some shaky ground. When Obama's infamous red line was crossed, before striking he asked Congress for authority to do so, but Congress didn't have the votes to pass it. While strictly speaking a president needs Congressional approval for military action, as Rachel Maddow pointed out in her book Drift Congress has been ceding it's authority in this regard for a long time. More details here.
Then there's Trump's hypocrisy. Let me count the ways. In 2013 when Obama had this same decision Trump tweeted that he shouldn't strike in Syria and if he did, he'd need Congress' approval to do it. Well Trump blew through both of those. Trump said he was moved by the babies being killed, but they've been killing in Syria for years now, and does it matter if they're killed by chemical weapons or conventional ones? He's still banned refugees from this conflict from coming to the US.
Trump ran on a secret 30 day plan to eliminate ISIS, which was obviously bullshit, but also on otherwise being more isolationist. A week ago Rex Tillerson, Sean Spicer and Nikki Haley all said that removing Assad was no longer a priority. There's talk that this may have emboldened Assad, but it's hard to say. A big question for me was how impulsive was Trump's decision, that's the fear that many have of his administration. Did this somehow get to him and was this Trump treating military response the same way he tweet-rants at 6am?
Jeffrey Goldberg writes that this is the end of the Obama Doctrine. Obama told him he was proud of his 2013 decision, to avoid the conventional Washington wisdom that limited military response would have a good outcome in the middle east. He took a lot of heat for that and Lots of former Obama advisors are cheering Trump's action. But unlike Trump has shown so far, Obama made the decision deliberately, thinking a few moves into the future. Is this the start of another middle quagmire? How slippery is this slope and will the military-industrial complex lead Trump to push for regime change. Syria's allies are Russia and Iran, they're already angered, what will that lead to? At least Trump called Russia just before the strikes to warn them (and to prevent their forces from being hit). That was a responsible thing to do and something I'm sure some military advisor suggested to Trump. I wonder if Trump will re-evaluate the role of the State Department in world affairs instead of just military force.
So Trump gave a measured response, sending cruise missiles to the airport used to launch the strikes. He didn't hit chemical weapons storage sites there (for fear of spreading them). These missiles can't do a lot of damage to the runways and already Syria launched fighters from that airport, so it doesn't seem like much damage was done. A couple of days ago Hillary Clinton spoke about striking all their airports and destroying Assad's entire Air Force, which is only a couple of hundred aircraft. That seems way more extreme, but also more likely to affect Assad's ability to attack the rebels and more likely to save lives.
The real question is how does Trump react a few days from now when Syria hasn't changed in any significant way.
I don't know what the answers are. I do know that in my list of complaints about Trump, this isn't all that high on my list. So far.