Right message, wrong doctrine.
Madonna has swerved into something she only dimly understands, that this situation in Syria is just none of the business of the US, poison gas or not. But her perspective is that war, in and of itself, is BAD, regardless of whether the combatants would have any empathy for her view of the world. It would have nothing to do with national interests of the US, only the seemingly endless bloodshed and violence that appears to be pointless. Adding the weight of the US military to one side or other does not essentially change the dynamics, except to INCREASE the number of non-combatants who are maimed or killed as “collateral damage”.
Although Madonna did support Wes Clarke for president back in the day because of his military command experience so it is doubtful that she carries a personal commitment to non-participation in all wars. I’m positive that she would validate the right of Israel to defend itself, at the least.