One problem with Obama’s statement on chemical weapons last summer was that he was sending a message to Assad that carnage up to that supposed red line was acceptable. But the red line itself was problematic. Given the limited flow of information coming out of Syria, it was always going to be difficult to confirm the use of chemical weapons. The conflicting signals from the State Department last week made the issue plain. “When this particular message came in from consulate Istanbul,” said a State Department spokesperson, we “concluded at the time that we couldn’t corroborate it; we haven’t been able to corroborate it since either.”

Sure, the opposition might submit evidence that they’d been gassed, but how would anyone know if they were telling the truth? How would you verify their stories, or authenticate YouTube videos of people vomiting, choking, and dying? The Syrian rebels have an interest, after all, in bringing the United States into the conflict.

In any case, as outgoing defense secretary Leon Panetta explained earlier this month, it turns out the United States would only send in troops to secure Syria’s chemical weapons stockpile after Assad fell. The concern, said Panetta “is what steps does the international community take to make sure that when Assad comes down, that there is a process and procedure to make sure we get our hands on securing those sites?” In other words, as long as Assad is still in power, the White House is not going to do anything about his arsenal.

And even if it wanted to, said chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, how would it know when to move against chemical weapons?