Graham Allison, former Assistant Secretary of Defense and one of the founders of the Kennedy School at Harvard, wrote a book 11 years ago saying that such an attack was ultimately inevitable. In this riveting conversation from 2004 he lays out the facts and the reasoning behind his warning. The likely source of such an attack is no longer Osama Bin Laden. But as you listen ask yourself whether this analysis does not apply as well – or even more closely – to ISIS.