Chemical use to deter populace

the world at large cannot say yea or nay to what is fact in Syria. at best there are less than 50 individuals that have the bedrock data in which to say chemicals where used and over half have hidden agendas. the issue: did Al-Assad overtly or covertly order or sign off on the use of chemicals, more importantly did any one with authority order use of chemicals, if this was a fact then Al-Assad is responsible and any and all countries have a moral ethical and legal obligation to intervene on behave of the those killed and people whom will be killed, by anyone with the authority to make use of said chemicals by the Syrian government.