At some point, Assad gave up his chemical weapons (under Obama). Just as Khadafi had many years ago.
When Assad gave up his weapons, Russia removed them. The USA provided inspection and the job was completed.
That Assad would go back to chem weapons makes no sense.
None.
Taking out Khadafi made no sense either.
Well, it did from the MB loving America hating POS that infested the WH like a cockroach for eight years.