Probably just Obama talk. However it was made clear that the USA would "allow" (crazy, we would need to provide the courtesy to allow a country to defend itself) Israel to defend itself if Israel deems it necessary. The real horror will be if terrorists become owners of chemical weapons and they probably can for a price.  Once those weapons are in hiding in one of the secure hideouts, we could have them turned on us.  Our President appears to be childish in his understanding of the real world. Yes, probably just talk that chemical weapons would be going past the "red line."