Bulk data storage allows for the "potential of abuse", President Obama has said, as he announced plans to curb the National Security Agency's authority.
"While few doubt the legitimacy of spying on hostile states, individuals acting on their own is a new threat," Mr Obama said.
"These signals intelligence efforts have prevented multiple attacks and saved innocent lives, not just in the United States but around the globe. But the risk of government overreach has also become more pronounced".
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