With much of the world’s attention fixed on the drama playing out in the streets of Egypt, the civil war in Syria that has claimed as many as 100,000 lives grinds on in the shadows. But new allegations of massive chemical weapons use by the regime of Bashar al-Assad have once more brought Syria into focus and raised anew the question of what if anything more should be done to stop what is going on there.

The US, France and the UK have called upon the UN Security Council to undertake an urgent investigation of this latest evidence of possible chemical weapons use that may have caused the deaths of hundreds. Meanwhile, Barack Obama’s administration is in a huge predicament, much of its own making. The US president has, on several occasions, declared that Syrian use of chemical weapons would cross a “red line”, constituting a “game changer” that would alter his calculus of what the US was prepared to do.

What makes all this awkward and more is that the US essentially opted not to do anything when it became clear that the Syrian regime did use chemical weapons against its own citizens several months ago. To be precise, it chose not to respond with military force, but instead to open the possibility it would supply less radical, opposition forces with lethal weaponry. The reality that such support has been more rhetorical than real, and has done nothing to alter the military balance, makes US warnings appear empty.