Right now the west doesn't have the stomach for a war with Syria mainly because of politics. Assad is no match for a western army without putting boots on the ground it will be much harder to do and Assad as well as his chemical weapons he has decent air defenses, Scud missiles, MIG 29s and if he attacks Israel he will set the region alight like he promised to do. Right now he also has Russia giving him both political support and weapons. If he starts gassing people you can bet he will first probably find himself at war with Israel worried that next time round the gas could be on a Scud missile pointed at Tel Aviv. After Israel will come the US Fifth Fleet from the Gulf and an arab coalition. Assad would also find himself in a position where going into exile is no longer an option because he won't find anybody willing to give him asylum so its either a show trial and execution in Syria or a fair trial and execution of life in prison at an international court. If its found there to be even the slightest trace of gas in these grenades then within hours there will be Israeli jets dropping bombs on Damascus.
First refugees travelling on Hungarian bus arrive at Austrian border (Reuters)
from the article: Assad forces mull use of chemical weapons in Homs, opposition says