The terrorists behind the 9/11 attacks took advantage of vulnerabilities in a critical part of America's infrastructure—our air transportation system. Experts have pointed to similar vulnerabilities in our nation's food supply, our ports, and our chemical and nuclear facilities. Congress and the Bush administration responded to the threat of other such attacks by creating the Department of Homeland Security. But has the government done enough? What more should we be doing to defend against potentially devastating domestic terrorist attacks? And just how much can we do without infringing on our freedom and way of life? Peter Robinson speaks with Frances Edwards and Stephen Flynn.