By the end of his administration, Barack Obama had more or less washed his hands of the Syria problem; he continued to fight IS, but he no longer believed it was practically possible to broker a political deal that removed Assad from power. Hillary Clinton, on the other hand, was more sanguine; she supported a no-fly zone even though it created the potential for conflict with the Russians. Candidate Trump, for his part, suggested a deal with Assad and the Russians to focus on the destruction of IS. You could call that position foolish or heartless, but you couldn’t say it was logically incoherent.
But that was then, and this is now. Trump’s missile attack on the Syrians could be dismissed as a one-off effort to impress everyone with how tough he was without running any real risk of conflict. Shooting down a Syrian plane, on the other hand, creates the potential for war with Syria and Russia. It is a very big deal indeed.
There is a case to be made for what amounts to the Clinton position on a no-fly zone. The problem is that Trump hasn’t made it, either to the world or to the American people. No one can tell exactly what his position is, which is the way he likes it. That could result in the US and Russia stumbling unwittingly into war.
The only thing dumber than starting a superpower conflict over an issue that doesn’t affect our vital interests, without really intending to, would be to deliberately start a war to prove that you aren’t a Russian puppet. That could be on the table, too.