A little over two years ago, Secretary of Defense William Cohen used a prop on a national television appearance to dramatize the threat America faced from weapons of mass destruction.  The image that remained with most viewers was that of the Secretary of Defense holding up a five-pound bag of Domino sugar, claiming that a similar quanity of anthrax, dispersed over the city of Washington, DC, could kill over half the city's inhabitants.Yet the Department of Defense (DoD) as a whole has not rushed to embrace the mission of defending the homeland from such attacks. "We are not seeking to become involved in this." then-Deputy Secretary of Defense John Hamre said last year. "But we have been asked to be involved because we are the only part of the government that has the resources that can be mobilized." DoD's response to this threat is in part symptomatic of the overall federal response, which to date has been unfocused and hamstrung by a national security structure that was designed to face an entirely different foe.In the decade since the end of the Cold War, the threat of terrorist attacks in the United States became a primary concern of the administation, Congress and the general public. While the inital anxiety has yielded in some quarters to a reassessment of the threat, all concerned parties are scrutinizing the merits of the federal response that is taking shape.