The WMD tale is exclusively American - to make their own population toe the line. It's based on a single false source. An impostor named Curveball by the services, who previously had been kicked out by the German BND, who issued explicit warnings when he showed up in America.
https://en.wikipedia.org/wiki/Curveball_%28informant%29
https://en.wikipedia.org/wiki/Curveball_%28informant%29