The use of chemical weapons against anyone is to be absolutely condemned. The outrage about their use in Syria appears to be because of the indiscriminate killing of civilians and especially children. However the use of tanks, artillery, helicopter gunships and air force bombers has killed many thousands more civilians than have been killed by chemical weapons. Why the selective outrage and calls for reprisals.
Any involvement, directly or indirectly, by any western powers will only bring wider grief and expansion of the conflict and incite a Muslim backlash.
It is up to the United Nations to act.