Politicians would like science to provide absolute answers. They do it all the time, whether on mad cow disease or whatever. The reality is that scientists look at the evidence available at the time, and they draw a conclusion from the evidence available at the time. All the evidence I have leads me to the conclusion that DU is not responsible. Am I excluding the possibility that something in the future may come up that would make me change my mind? I cannot completely exclude that possibility, but I think it's highly unlikely.
On February 26th, 2013. See this statement in context.