How does punative strikes, except as a warning not to do it again?
The ever diminishing "punitive strikes" will do nothing good, and a lot of harm.
A punitive strike using nukes that obliterated Assad's entire military would send a message that could not be ignored.
Pinpricks, as are being proposed, will just show Assad that he can stand up to the US and not have to worry.
Best just to leave well enough alone.