McClatchy reports that the evidence for use of chemical weapons in Syria is not that strong:

The intelligence findings cited in a letter from the White House to Capitol Hill on Thursday were of “low or moderate” confidence, said a U.S. intelligence official who requested anonymity in order to discuss the classified reports. Another person familiar with the issue, who asked not to be further identified because of its sensitivity, said that only a minuscule trace of a “byproduct”– a toxic residue left behind after use of a nerve agent, and which he did not identify – had been found in a soil sample [bold mine-DL]. “They found trace amounts of a byproduct in soil, but there are also fertilizers that give out the same byproduct,” the person said. “It’s far from conclusive.” [bold mine-DL]

It’s not credible to review this evidence and conclude that the U.S. has to intervene militarily in Syria. There’s nothing here that demands U.S. military action. Of course, that hasn’t stopped the usual suspects from demanding precisely that, but this just shows why their judgment on this issue can’t be trusted.

Later in the article, chemical weapons experts cast doubt on the use of sarin:

Richard Guthrie, formerly project leader of the Chemical and Biological Warfare Project of the Stockholm International Peace Research Institute, said the number of those affected appears low. He said, for example, the Tokyo underground attacks in 1995 that involved a small amount of sarin resulted in 13 deaths and more than 1,000 wounded. “Any kind of a large-scale attack would have left a lot of dead, and a lot more showing symptoms,” Guthrie said. Even if there was certain sarin contamination, he said the apparent small effect would raise questions about whether it might have been the result of a mistake, a rebel attack somehow damaging a Syrian chemical weapon in transit, or as happened on several occasions in the Iran-Iraq war, a single poorly labeled artillery shell being used accidentally [bold mine-DL].

If you hear politicians or pundits declaring that a “red line” has definitely been crossed in Syria on the basis of this paltry evidence, it seems clear to me that you should dismiss their statements and assume that they’re poorly informed or arguing in bad faith.