President, first lady lead moment of silence
The president and first lady lead the nation in a moment of silence to mark the first plane strike on September 11.
17 years later: Are we safer?09:25
How has the fight against terror changed since 9/11?06:00
Why Al Qaeda could be stronger and more dangerous than before02:55
Hadley on 9/11: 'There is more work to be done on prevention'04:33
#BIGPICTURE: One World Trade Center above the clouds00:29
How the US has changed since Sept. 11, 200118:31