When I saw the words ‘America’s moral authority’ in the headline I immediately thought, “Caitlin’s done a comedy post to give us a weekend laugh.”
As you say, white phosphorus is hardly a moral way of conducting warfare, and we could also point to the highly questionable provenance of Assad’s gas attacks, the real role of US ‘military advisers’ in Saudi Arabia’s genocidal conflict with Yemen.

OK, as yet I’ve heard of no allegations concerning white phosphorus or any illegal weapons in the latter, but supporting the side using air strikes targeting supply likes and infrastructure, thus causing food and water shortages, or targeted strikes on hospitals and medical centres in the latter conflict again hardly constitutes a display of moral authority.