A US programme, which allows the National Security Agency (NSA) to store millions of phone calls made by Americans, is being investigated in Congress.<br /><br />Members of a committee appointed by President Barack Obama have been testifying on the controversial use of metadata spying.<br /><br />The panel found that there was no evidence that the NSA's mass surveillance had prevented any attacks.<br /><br />But for some members of Congress, the question is whether President Obama will address the concerns raised by leaker Edward Snowden's documents on Friday.<br /><br />Al Jazeera's Shihab Rattansi reports from Washington DC.
