TODAY | June 19, 2013
>>> we are learning more about the government's secret surveillance programs that chuck mentioned and the terror attacks they say they have thwarted and we expect more details today on capitol hill . andrea mitch southern land in washington. andrea, good morning.
>> reporter: good morning. today it is robert muller 's turn to face the questions on capitol hill about how edward snowden was able to pull off what appears to be one of the worst security leaks in american history even as the hunt for snowden continues. while snowden threatens more leaks to come, intelligence officials are trying to recreate his computer trail and assess the damage. nsa director keith alexander telling congress tuesday the leaks foiled 20 terror attacks since 9/11, including 10 in the u.s.
>> these are critical to protect our nation and allies security.
>> reporter: he said in two newly declassified cases they helped crack. first a plot to blow up the new york stock exchange between 2007 and 2010 . monitoring a suspected terrorist in yemen lead them to a kansas city man, a naturalized citizen who was channelling money to al qaeda operatives planning to blow up the exchange. he ended up pleading guilty to bank fraud and money laundering . second lead to a group in so ma -- somalia.
>> the fact that the program lead to the direct disruption doesn't prove if they had been doing it in a narrow way directing at people only to believe they were engaged in terrorism they wouldn't have stopped the same plots.
>> reporter: the agency is rethinking it's system in snowden 's wake. what we have to do is think how did he do that? what did he do? where was that?
>> reporter: before leaving the he was joking about taking the heat over the controversy.
>> thank you sean.
>> good to see you.
>> tell your boss i owe him a beer.
>>> moments ago in germany the president defended that.
>>> thank you very much.