He also speculated that in order to justify an attack on Iran using nuclear weapons, US authorities might make a false, but difficult to disprove, claim that Iranian biologists are trying to develop a strain of the H5N1 avian flu virus which would be transmissible from human to human, and which would be transported to Europe by birds migrating north with the onset of the northern summer of 2006. Later, a human to human transmissible strain was found to have emerged in Southeast Asia and is documented by the WHO.