deputy fbi director sean joyce said the web traffic program had contributed to arrests averting a plot to bomb the new york stock exchange that 3 years ago ( cnn ) - in a hearing tuesday with the house permanent select committee on intelligence , the director of the national security agency , keith alexander , said that since 911 , there have been more than 50 terror plots thwarted with the help of nsa surveillance programs .
text size - + reset obama defends nsa officials are set to disclose information about the other cases in a private session with lawmakers on wednesday .
( photos : pols , pundits weigh in on nsa report ) alexander said the programs were subject to “ extraordinary oversight .
i hope today in this hearing we were able
alexander said at least 10 of the attacks were set to take place in the united states , suggesting that most of the terrorism disrupted by the program had been set to occur abroad .
the data on use of the call - tracking data came in a fact sheet released to reporters in connection with a public house intelligence committee hearing exploring the recently leaked telephone data mining program and another surveillance effort focused on web traffic generated by foreigners .
( politico junkies : nsa leaks cause flood of political problems ) alexander said 90 percent of the potential terrorist incidents were disrupted by the web traffic program known as prism .
” ” this is n’t some rogue operation that a group of guys up at nsa are running , ” the spy agency ’s chief added .