Military intervention no option

Following August 21's chemical attack on Ghouta near Damascus that killed some 300 people, Western powers led by the US have been seriously considering a punitive action against Syria. US, Britain and France blame the attack on Syrian government, but the latter denies it.
What does the West exactly hope to achieve, if it chooses to embark on military action against Syria? Will air or missile strikes on a few military targets force the regime of President Assad to stop what amounts to persecution of its own people? And, what is the guarantee that it won't degenerate into a larger war drawing Syria's neighbours into the fray and create a situation like that of Iraq invasion in 2003 or of Libya in 2011?
In all probabilities, such a military action will only add further fuel  to the already raging  flame of civil war that has killed around 1,00,00 people and forced some two million people to seek refuge in neighbouring countries. Worse still, the ruling clique in Damascus may use this attack to its advantage and whip up pan-Arab nationalistic jingoism against West. Syria's allies like Iran, Russia and China, who have warned against such military action, would only find further justification to provide increased moral  and material support to the brutal Assad regime.
Rather than going for a 'calibrated' military action, the West should make a serious move towards a peaceful solution to the Syrian crisis. They must engage Syria's allies like Russia and China in such a peace talk, preferably under a legally binding UN resolution, to end the civil war and establish lasting peace in the country.