While inaction could lead to terrible results, unwarranted action could easily result in much worse.
The last example of catastrophic intervention was the US-led invasion of Iraq. This, too, was unilaterally based on intelligence into which our leaders read certainty. It is now proven that the intelligence was bad and the invasion a terrible mistake.
We, the public, do not know who is using chemical weapons in Syria. Knowing this administration's promise not to allow the government in Syria to use weapons of such mass destruction, it would not be wise for Assad to use them, and a masterstroke for the rebels. Secret intelligence was not, cannot be enough. Unpublished, it cannot face scrutiny from US.
Don't be Bush.
Don't be MacNamara.
Do the smart thing, wait for the inspections.