AUDIE CORNISH, HOST:
Saying that Syria has used chemical weapons is a major step for the administration. But as we've heard, there's still a lot we don't know about the evidence the White House is relying on.
Joining us now to discuss those uncertainties is NPR's Larry Abramson. And, Larry, what is known about the evidence that the administration is citing and how the U.S. got a hold of it?
LARRY ABRAMSON, BYLINE: The administration isn't saying much at all about how it got this information, saying that this is intelligence information that they can't elaborate on. The letter to Congress that we've been hearing about does refer to physiological samples, and that seems to indicate that we got some kind of evidence from actual victims of this supposed attack.
Now, NPR has sources of the region, doctors who say that they've responded to patients who say that they were experiencing symptoms consistent with the use of chemical weapons, and that these doctors say they're sending samples of tissue to the United States. But we don't know whether that's the same type of evidence that the intelligence community is looking at.
And in any case, even if that's true - as the White House letter notes - that would raise questions about the chain of custody, who was handling these samples. And if they were handled by members of the Syrian opposition, who have an interest in saying to the West that Assad has been using chemical weapons, we might not want to trust that information. And remember, there are other sources besides physiological samples - photography and other information - that led the U.S. to believe that Syria loaded chemical weapons into artillery shells just a few months ago.
CORNISH: And given all that then, how confident are intelligence officials about this assessment?
ABRAMSON: Well, you remember about a decade ago, the head of the CIA said intelligence about weapons of mass destruction in Iraq was a slam dunk. And that is the ultimate cautionary tale in this case. This does not appear to be a slam dunk. One official told NPR this was a strong maybe. And he indicated that there are varying levels of certainty among different intelligence agencies.
Now if that sounds familiar, you may remember that just a few weeks ago, we heard that there are varying levels of a certainty about whether or not North Korea can make small nuclear weapons that can fit on missiles. So there's clearly a need to get more information from the scene, in particular, soil samples. That would involve getting onto Syrian territory. The U.N. is trying to do that. And the White House letter to Congress endorsed that U.N. effort of something that would take the investigation further. But that effort has been thwarted by Syrian resistance.
CORNISH: And do we know the scale of the use of these weapons and whether people died as a result?
ABRAMSON: We don't. The White House officials refused to even confirm that there were deaths. One official told us that there were deaths involved. But the White House letter says that this was the use of chemical weapons on a small scale. And it's an open question whether the U.S. would take military action or try to secure these weapons if we're only talking about a handful of deaths. So that would be a big step to take if it wasn't a large massacre.
CORNISH: That's NPR's Larry Abramson. Larry, thank you so much.
ABRAMSON: Thank you. Transcript provided by NPR, Copyright NPR.