Five years ago, as we are constantly reminded, the world changed. Al Qaeda operatives, employing hijacked passenger airliners as guided missiles, destroyed the World Trade Center and ploughed into the Pentagon . A fourth hijacked airliner, possibly aimed at the White House, crashed in a field in Pennsylvania. In all, some 3,000 lives were lost. The date was 11 September 2001, a day rivaled in infamy for Americans only by an earlier date, 7 December 1941. To mark the fifth anniversary of that day of devastation, we asked former Navy Secretary John Lehman, an outspoken member of the commission that investigated the 9/11 attacks, to address the question of whether the nation is safer today than it was then.