August 20, 2012:

“We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus,” Obama said. “That would change my equation. . . . We’re monitoring that situation very carefully. We have put together a range of contingency plans.”

Then we have this:

Analysts believe it's possible people in the video were deliberately exposed to a "caustic" agent such as chlorine. But that would not be the same as using a chemical weapons as defined by international treaties, such as a nerve or blister agent.

"Something went down, but it was short of a chemical weapon," a senior State Department official told CNN. The official was speaking on condition of anonymity for the same reason as the other two officials.

Nice dance around by those 'analysts' and the 'senior State Department official.'

Here is the definition of 'chemical weapons' as we find it in Article II of the Chemical Weapons Convention:

1. "Chemical Weapons" means the following, together or separately:
(a) Toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes;
(b) Munitions and devices, specifically designed to cause death or other harm through the toxic properties of those toxic chemicals specified in subparagraph (a), which would be released as a result of the employment of such munitions and devices;
(c) Any equipment specifically designed for use directly in connection with the employment of munitions and devices specified in subparagraph (b).

Deliberately exposing people to a 'caustic' agent, such as chlorine, by definition is the employment of a 'chemical weapon.' There is no requirement that it be 'weaponized' in a high tech delivery system; there is no requirement that the toxic chemical be specifically designed to be used as a 'weapon' and there is no specific definition of chemicals, materials, or delivery systems.

Obama drew his 'red line' in the sand, and now he's hedging, badly,

By the way, there are 188 signatories to the Chemical Weapons Convention. The United States is one of them. To what other 'international treaties' was the 'U.S. military official directly familiar with the preliminary analysis' referring?