Homeland Security Chief Michael Chertoff's eyes narrow and his voice develops a stern, urgent tone as he reveals America's biggest vulnerability to terrorism."The great weapon they have is persistence and patience, and the one weakness that we have is the tendency to lose patience and become complacent," Chertoff tells WTOP.
"It strikes me as hard to accept that anybody would believe the threat is over. There is nothing these terrorists are doing or saying that could lead a reasonable person to believe that they have somehow lost interest. Our biggest challenge is making sure we do not drop our guard because time passes."
Chertoff recognizes it has been more than six years since al Qaida launched the Sept. 11 attacks, but some experts say that's how long it took to plan them, suggesting the U.S. may close in on another spectacular attempt by Osama bin Laden to topple the U.S. economy.
"If you're asking me what keeps me up at night or what I most worry about -- in the short term, obviously, you worry about homegrown terrorists or somebody coming in with an explosive device or the kind of act of violence or terror that we've actually seen occasionally carried out in this country by people who are simply nuts or like a Timothy McVeigh.
"But in the longer run, in terms of something that would really be earth-shattering, the kinds of things I'm worried about are a nuclear or a dirty bomb attack or a nuclear or biological attack...
