President Obama said in Sweden today that he personally "didn't set a red line" on Syria:
"First of all, I didn't set a red line," said Obama. "The world set a red line. The world set a red line when governments representing 98 percent of the world's population said the use of chemical weapons are [inaudble] and passed a treaty forbidding their use, even when countries are engaged in war. Congress set a red line when it ratified that treaty. Congress set a red line when it indicated that in a piece of legislation entitled the Syria Accountability Act that some of the horrendous things happening on the ground there need to be answered for. So, when I said in a press conference that my calculus about what's happening in Syria would be altered by the use of chemical weapons, which the overwhelming consensus of humanity says is wrong, that wasn't something I just kind of made up. I didn't pluck it out of thin air. There's a reason for it."
And here's video of Obama setting a "red line" in regard to Syria, from over a year ago:
And here's a background call in April 2013 with “a White House official” that left no doubt about what President Obama's own officials thought about where the red line came from:
We go on to reaffirm that the President has set a clear red line as it relates to the United States that the use of chemical weapons or the transfer of chemical weapons to terrorist groups is a red line that is not acceptable to us, nor should it be to the international community. It's precisely because we take this red line so seriously that we believe there is an obligation to fully investigate any and all evidence of chemical weapons use within Syria.
...it is absolutely the case that the President's red line is the use of chemical weapons...
And this one is especially devastating:
And the people in Syria and the Assad regime should know that the President means what he says when he set that red line. And keep in mind, he is the one who laid down that marker. He's the one who directed that we provide this information to the public. And he's the one who directed that we do everything we can to further investigate this information so that we can establish in credible, corroborated, factual basis what exactly took place.