The Kings of War blog wisely argues against military action against Syria. Reasons include:
The responsibility to protect is not the responsibility to punish. Leave that to the ICC. The war crimes commission can act in due course. That’s of course unless the government wish to give the Russian and Chinese government the press release that says ‘the west doesn’t give a monkeys about international process’. The same should be the case for the need to secure UN resolutions
The unintended consequence of action is to alienate those within the regime who might have been sought out to negotiate. Or who might have been alienated by the use of the chemicals in the first place. All action solidifies the resolve of the regime.
You might hit Russian advisors. That would be ill-advised.