U.S. officials report no specific threats against the nation as the 9/11 anniversary nears. Still, Americans' nerves are on edge. news_military_planes_rts.jpg home Nation on Alert http://abcnews.go.com/sections/wnt/videofiles/Video/020909wnt_nation_video.ram 10316696820680 abcnews.gif video.gif http://abcnews.go.com/sections/wnt/videofiles/Video/020909wnt_nation_video.ram 10316696820681 PLAY lock_icon.gif lock_icon.gif lock_icon.gif big_headline