US will continue to gather foreign intelligence: WH official

The US has asserted that it will continue to gather foreign intelligence, which it argued is essential to keep the nation and allies safe, amid report that National Security Agency monitored the phone conversations of 35 world leaders.

At the same time, President Barack Obama has sought review of intelligence gathering including with respect of foreign partners.

"We want to ensure we are collecting information because we need it and not just because we can," Lisa Monaco, assistant to the US President for the Homeland Security and Counter-terrorism, wrote in an op-ed in USA Today.

The White House has also created the President's Review Group on Intelligence and Communications Technology to provide recommendations on these issues, and the Privacy and Civil Liberties Oversight Board is reviewing counter-terrorism efforts to ensure that privacy and civil liberties are appropriately protected as well, she said.

"Going forward, we will continue to gather the information we need to keep ourselves and our allies safe, while giving even greater focus to ensuring that we are balancing our security needs with the privacy concerns all people share," Monaco wrote.

According to a classified document provided by former CIA contractor Edward Snowden, one unnamed US official handed over 200 numbers, including those of the 35 world leaders, none of whom is named. These were immediately "tasked" for monitoring by the NSA, the Guardian daily reported.

The revelation has triggered diplomatic tensions between the US and its allies, as German chancellor Angela Merkel on Wednesday accused the US of tapping her mobile phone.

Acknowledging that series of unauthorised disclosures of classified information have led to criticisms of US intelligence activities, Monaco said these disclosures have created significant challenges in our relationships with some of America's closest foreign partners.

"To be clear: Our intelligence capabilities, and the dedication of the men and women who work in the US intelligence community, including at the NSA, are beyond compare. Their contributions and sacrifices are a significant reason we have enjoyed relative security since 9/11."

Monaco wrote, no one disputes the need for careful, thorough intelligence gathering. Nor is it a secret that US collects information about what is happening around the world to help protect its citizens and allies. "So does every intelligence service in the world," she wrote.

"While our capabilities are unmatched, the US government is not operating unrestrained. We are not listening to every phone call or reading every e-mail. Far from it. There are legal limits to what the NSA can and cannot do, and the recent disclosures and additional documents the government has declassified prove just how seriously the NSA takes these limits," Monaco said.