YOU HAVE TO BELIEVE IN IDEAS TO SELL THEM:

Where Obama's strategy is weakest is in reaching ordinary people: the networked web of human relationships that transmits rage, hatred, and despair or hope, trust, and loyalty. His doctrine that the US will use force to defend its "core interests," but will mobilize others "to address broader challenges to international order," is sound logic and good politics in a war-weary US. But, as a Syrian tweeted to me, what the world hears Obama saying is that the US will use force to avenge the deaths of two American journalists, but will stand by while 200,000 Syrians are slaughtered.

Unless US military action is seen as actually protecting the lives and property of the Iraqi and Syrian people, the US will quickly lose the propaganda war to the Islamic state. 

As many experts warn, the first time a drone strike kills a woman or child, a video of the scene and the funeral will be posted for the Muslim world to see.

Even if that video does not actually increase support for the Islamic State, it will convince millions of Muslims that the US is up to its old military tricks: bombing for oil, or for Israel, or simply to crush all Muslims. Those anti-American attitudes, newly hardened once again, will make it much more difficult to get the necessary intelligence against the Islamic State on the ground and to deprive them of the support of other Sunni militias.

That will not just hurt the US in Syria and Iraq. It will shape popular views in other Arab states, limiting their governments' ability to work with the US. Most damaging of all, a purely strategic justification for military action - in defense of core US interests - leaves no room to do what actually needs to be done in Syria.

The only way to bring Syrian President Bashar al-Assad to the negotiating table is to weaken him and the Islamic State simultaneously. And the only legal or moral justification for striking his air force, ammunition dumps, or heavy weaponry is the international responsibility to protect his people from him - just as the US helped to protect the Yezidis from the Islamic State.

For, contrary to Obama's claim, the brutality of the Islamic State is not "unique." Assad has killed more than 200,000 people, mostly civilians, in a conflict that started with his government's torture of children.

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