But, of course, he needs to know what exactly the U.S. meant when it referred to CW use as a “red line.”  If it turns out that this phrase is empty of content, then the way will be clear for a far larger use of these materials as and when the regime deems necessary.

Much therefore now depends on the response of the Obama administration in the days ahead.

As of now, it seems likely that Assad will not be disappointed. The line currently emerging from statements by senior U.S. officials is that the facts are not yet all in, and so further investigation is necessary before any policy conclusions can be drawn. The U.S. government is now calling for a “comprehensive United Nations investigation” to “credibly examine the evidence and establish what took place.”

The possibility of Assad permitting such an investigation is zero. The regime has already refused – setting absurdly narrow conditions in recent weeks for the entry of an existing team, which as a result has found it impossible to begin its work.

So unless this line changes in the days ahead, it appears the dictator can record that the use of chemical weapons can be safely included on the list of military means to be employed against the rebellion and its supporters — as and when deemed necessary.

In his clearest statement regarding the issue of chemical weapons in Syria, on March 21 of this year, President Obama said: “I’ve made it clear to Bashar al-Assad and all who follow his orders: We will not tolerate the use of chemical weapons against the Syrian people. … The world is watching; we will hold you accountable.”

This statement does not include an explicit threat of force against the regime. But it is nevertheless fairly unambiguous. The key words are “not tolerate the use of chemical weapons.”

Chemical weapons have been used. The latest statements by administration officials indicate that tolerating their use, in the sense of taking no action in response, is precisely what Washington is now set to do.