The other nations are also spying on the US and other countries, said Clapper, adding that such spying is essential and invaluable to know how these states will act toward the US, reports the NYT.
They also added that the gathering of Europeans' phone records was not executed by US spy agencies, but local ones of NATO states that have then turned them over to the NSA as per previous agreements.
But while some of the committee's members railed against the accuracy of the reports about US spying and data collection in Europe, others, like Senator Dianne Feinstein, the chairwoman of the committee and strong supporter of US surveillance operations, has said that she does not believe the US should tap communications of friendly foreign members of state.
Nevertheless, most agreed that a review of the surveillance practices is inevitable.
The jury is still out on whether US president Barack Obama was made aware of the tapping of the phones and emails of several European and Latin American heads of state - the NSA claims he knew, the administration that he didn't - but Obama has finally initiated the aforementioned review, as he told to ABC News.
"We're undergoing a complete review of how our intelligence operates outside of the country," he said, but hasn't mentioned a review of national operations for now.
Also, according to an unnamed US government official, he also instructed the NSA to stop monitoring UN diplomats. As a reminder: a recent report by German Der Spiegel base on the documents shared by EDward Snowden has revealed that the NSA has spied on United Nations' officials and personnel after managing to compromise the encryption of the organization's internal video conferencing system.
Senator Feinstein also claims that the The White House has informed her that collection on US allies will not continue.