re: "authority...attack another government"....how about moral authority.  I am no fan of Trump but this time he has done the right thing.  Syria is a mess..the only way to clean it up is to take all of the combatants out of the picture and  occupy the country with a UN /Arab League backed  military presence until the country gets back to some semblance of normal. Assad, meanwhile goes on trial for crimes against humanity along with the head of Isis..