The Syrian government forces have already demonstrated they can effectively beat the rebel jihaidsts in other parts of Ghouta without resorting to chemical weapons.
Chemical weapons labs were uncovered in the parts of Ghouta recently taken back from the jihadits forced to abandon their positions.
The jihadist rebels have repeatedly used civilian populations in Syria as human shields, so it is known they will sacrifice innocents if it suits them.
No previous chemical attack has managed to kill a single rebel fighter, only civilians.
Trump blamed Syria. Was he wrong?