French journalist Nicholas Hénin was held hostage by Isis for ten months. His reasons for not bombing Syria are well worth reading. Here are a couple of quotes from a piece in The Guardian.
“Strikes on Isis are a trap. The winner of this war will not be the parties that have the newest, most expensive, most sophisticated weaponry, but the party that manages to have the people on its side... At the moment, with the bombings, we are more likely pushing the people into the hands of Isis. What we have to do, and this is really key, we have to engage the local people. As soon as the people have hope in the political solution, then Islamic State will just collapse. It will have no ground any more. It will collapse.”
Hénin can also be found on The Syrian Campaign, home site for a non profit based in the UK, and well worth checking out.