I agree that there are no easy solutions to the conflict in Syria. I'd hate to be the PM. Like her or loathe her, Mrs May has had, as far as I can remember, the most gruelling of Premierships. Cameron passed her the poisoned chalice so she's negotiating Brexit with Barnier and Juncker, chemical weapons have been used against a spy on UK soil, she's had to call out Russia, unite most of the western world in condemnation of Russia, assess the crisis in Syria, and all the time she's had to play ball with one of the strangest POTUS to ever hold office.
The Syrian situation is complex and is a no win situation. There are reasons for us to show our might against evil regimes, to prevent the normalisation of chemical weapons, but reasons to back off as well, as mentioned by others.
All the time we are reminded of Blair's choices. I imagine such thoughts are uppermost in the minds of TH and the military strategists advising her.
It begs the question: what would Corbyn do, if anything?