Attorney General John Ashcroft says a U.S. citizen with al Qaeda ties has been arrested in connection with a plot to explode a radioactive dirty bomb. exclusivelyr1b.gif hn_pol_ashcroft_john_rts.jpg l Bomb Plot Foiled abcnews.gif video.gif http://start.real.com/rd?pid=abcchan&url=020610ashcroft.rm&rpcontexturl=abcnews.go.com/webcasts/realone/todaysfeature_frameset.html&rpurl=abcnews.go.com/sections/us/DailyNews/chicagosuspect020610.html#realone PLAY webpage.gif http://news.real.com/? MORE rotary_default