One of the points is that just only the fact of “showing evidences” like that should make you think about theater. Data is a thing, facts is another thing, and showing “evidences” is show business. Which intent should be clear now at least in the Powell's performance. And this one should have taught us to be skeptic, to start with. They created a specious excuse to attack. We shouldn't say “yeah there were evidence that he used the gas against his own people”. To cut it short, it's a fake (news). The explanation given make sense: they hit a rebels' deposit of weapons, and it happened to contain rebels' chemical weapons. This fits the number of deaths, too few if the attack would have been carried with chemical weapons from airplanes, and also the pics of rescuers without suits, needed in case the gas concentration would have been compatible with an actual attack.